diff --git a/blocks/logic.js b/blocks/logic.js
index 8de2ae6d4..c5f156a81 100644
--- a/blocks/logic.js
+++ b/blocks/logic.js
@@ -468,7 +468,7 @@ Blockly.Constants.Logic.CONTROLS_IF_MUTATOR_MIXIN = {
       i++;
     }
     // Rebuild block.
-    for (var i = 1; i <= this.elseifCount_; i++) {
+    for (i = 1; i <= this.elseifCount_; i++) {
       this.appendValueInput('IF' + i)
           .setCheck('Boolean')
           .appendField(Blockly.Msg['CONTROLS_IF_MSG_ELSEIF']);
diff --git a/blocks/procedures.js b/blocks/procedures.js
index 591a751a1..1c29e7583 100644
--- a/blocks/procedures.js
+++ b/blocks/procedures.js
@@ -372,17 +372,18 @@ Blockly.Blocks['procedures_defnoreturn'] = {
     // Add options to create getters for each parameter.
     if (!this.isCollapsed()) {
       for (var i = 0; i < this.argumentVarModels_.length; i++) {
-        var option = {enabled: true};
+        var argOption = {enabled: true};
         var argVar = this.argumentVarModels_[i];
-        var name = argVar.name;
-        option.text = Blockly.Msg['VARIABLES_SET_CREATE_GET'].replace('%1', name);
+        argOption.text = Blockly.Msg['VARIABLES_SET_CREATE_GET']
+            .replace('%1', argVar.name);
 
-        var xmlField = Blockly.Variables.generateVariableFieldDom(argVar);
-        var xmlBlock = document.createElement('block');
-        xmlBlock.setAttribute('type', 'variables_get');
-        xmlBlock.appendChild(xmlField);
-        option.callback = Blockly.ContextMenu.callbackFactory(this, xmlBlock);
-        options.push(option);
+        var argXmlField = Blockly.Variables.generateVariableFieldDom(argVar);
+        var argXmlBlock = document.createElement('block');
+        argXmlBlock.setAttribute('type', 'variables_get');
+        argXmlBlock.appendChild(argXmlField);
+        argOption.callback =
+            Blockly.ContextMenu.callbackFactory(this, argXmlBlock);
+        options.push(argOption);
       }
     }
   },
diff --git a/core/block_svg.js b/core/block_svg.js
index c340576be..a1d41800f 100644
--- a/core/block_svg.js
+++ b/core/block_svg.js
@@ -700,8 +700,8 @@ Blockly.BlockSvg.prototype.showContextMenu_ = function(e) {
     if (this.workspace.options.disable && this.isEditable()) {
       // Option to disable/enable block.
       var disableOption = {
-        text: this.disabled ?
-            Blockly.Msg['ENABLE_BLOCK'] : Blockly.Msg['DISABLE_BLOCK'],
+        text: this.isEnabled() ?
+            Blockly.Msg['DISABLE_BLOCK'] : Blockly.Msg['ENABLE_BLOCK'],
         enabled: !this.getInheritedDisabled(),
         callback: function() {
           var group = Blockly.Events.getGroup();
@@ -936,7 +936,7 @@ Blockly.BlockSvg.prototype.dispose = function(healStack, animate) {
  * Change the colour of a block.
  */
 Blockly.BlockSvg.prototype.updateColour = function() {
-  if (this.disabled) {
+  if (!this.isEnabled()) {
     // Disabled blocks don't have colour.
     return;
   }
@@ -999,7 +999,7 @@ Blockly.BlockSvg.prototype.setShadowColour_ = function() {
  * Enable or disable a block.
  */
 Blockly.BlockSvg.prototype.updateDisabled = function() {
-  if (this.disabled || this.getInheritedDisabled()) {
+  if (!this.isEnabled() || this.getInheritedDisabled()) {
     var added = Blockly.utils.dom.addClass(
         /** @type {!Element} */ (this.svgGroup_), 'blocklyDisabled');
     if (added) {
diff --git a/core/blockly.js b/core/blockly.js
index 832a6af42..e42ad533e 100644
--- a/core/blockly.js
+++ b/core/blockly.js
@@ -107,7 +107,7 @@ Blockly.clipboardTypeCounts_ = null;
 
 /**
  * Cached value for whether 3D is supported.
- * @type {!boolean}
+ * @type {?boolean}
  * @private
  */
 Blockly.cache3dSupported_ = null;
@@ -181,9 +181,9 @@ Blockly.svgResize = function(workspace) {
 // TODO (https://github.com/google/blockly/issues/1998) handle cases where there
 // are multiple workspaces and non-main workspaces are able to accept input.
 Blockly.onKeyDown_ = function(e) {
-  var workspace = Blockly.mainWorkspace;
-  if (workspace.options.readOnly || Blockly.utils.isTargetInput(e) ||
-      (workspace.rendered && !workspace.isVisible())) {
+  var mainWorkspace = Blockly.mainWorkspace;
+  if (mainWorkspace.options.readOnly || Blockly.utils.isTargetInput(e) ||
+      (mainWorkspace.rendered && !mainWorkspace.isVisible())) {
     // No key actions on readonly workspaces.
     // When focused on an HTML text input widget, don't trap any keys.
     // Ignore keypresses on rendered workspaces that have been explicitly
@@ -247,7 +247,7 @@ Blockly.onKeyDown_ = function(e) {
     } else if (e.keyCode == 90) {
       // 'z' for undo 'Z' is for redo.
       Blockly.hideChaff();
-      workspace.undo(e.shiftKey);
+      mainWorkspace.undo(e.shiftKey);
     }
   }
   // Common code for delete and cut.
diff --git a/core/bubble.js b/core/bubble.js
index d5b9f31b1..fe72b2c64 100644
--- a/core/bubble.js
+++ b/core/bubble.js
@@ -374,7 +374,7 @@ Blockly.Bubble.prototype.registerResizeEvent = function(callback) {
 
 /**
  * Move this bubble to the top of the stack.
- * @return {!boolean} Whether or not the bubble has been moved.
+ * @return {boolean} Whether or not the bubble has been moved.
  * @private
  */
 Blockly.Bubble.prototype.promote_ = function() {
diff --git a/core/field.js b/core/field.js
index ecd8469cb..86fd29818 100644
--- a/core/field.js
+++ b/core/field.js
@@ -736,31 +736,19 @@ Blockly.Field.prototype.setValue = function(newValue) {
 
   var validatedValue = this.doClassValidation_(newValue);
   // Class validators might accidentally forget to return, we'll ignore that.
-  if (validatedValue !== undefined) {
-    newValue = validatedValue;
-  }
-  if (newValue === null) {
-    doLogging && console.log('invalid, return');
-    this.doValueInvalid_();
-    if (this.isDirty_) {
-      this.forceRerender();
-    }
+  newValue = this.validate_(newValue, validatedValue);
+  if (newValue instanceof Error) {
+    doLogging && console.log('invalid class validation, return');
     return;
   }
 
   var localValidator = this.getValidator();
   if (localValidator) {
-    var validatedValue = localValidator.call(this, newValue);
+    validatedValue = localValidator.call(this, newValue);
     // Local validators might accidentally forget to return, we'll ignore that.
-    if (validatedValue !== undefined) {
-      newValue = validatedValue;
-    }
-    if (newValue === null) {
-      doLogging && console.log('invalid, return');
-      this.doValueInvalid_();
-      if (this.isDirty_) {
-        this.forceRerender();
-      }
+    newValue = this.validate_(newValue, validatedValue);
+    if (newValue instanceof Error) {
+      doLogging && console.log('invalid local validation, return');
       return;
     }
   }
@@ -782,6 +770,27 @@ Blockly.Field.prototype.setValue = function(newValue) {
   doLogging && console.log(this.value_);
 };
 
+/**
+ * Process the result of validation.
+ * @param {*} newValue New value.
+ * @param {*} validatedValue Validated value.
+ * @return {*} New value, or an Error object.
+ * @private
+ */
+Blockly.Field.prototype.validate_ = function(newValue, validatedValue) {
+  if (validatedValue !== undefined) {
+    newValue = validatedValue;
+  }
+  if (newValue === null) {
+    this.doValueInvalid_();
+    if (this.isDirty_) {
+      this.forceRerender();
+    }
+    return Error();
+  }
+  return newValue;
+};
+
 /**
  * Get the current value of the field.
  * @return {*} Current value.
diff --git a/core/field_date.js b/core/field_date.js
index 730677bc2..20290fa68 100644
--- a/core/field_date.js
+++ b/core/field_date.js
@@ -36,7 +36,6 @@ goog.require('goog.date.DateTime');
 goog.require('goog.events');
 goog.require('goog.i18n.DateTimeSymbols');
 goog.require('goog.i18n.DateTimeSymbols_he');
-goog.require('goog.style');
 goog.require('goog.ui.DatePicker');
 
 
diff --git a/core/field_textinput.js b/core/field_textinput.js
index df82ee4d6..a79d55e03 100644
--- a/core/field_textinput.js
+++ b/core/field_textinput.js
@@ -134,7 +134,7 @@ Blockly.FieldTextInput.prototype.doValueInvalid_ = function() {
  * Called by setValue if the text input is valid. Updates the value of the
  * field, and updates the text of the field if it is not currently being
  * edited (i.e. handled by the htmlInput_).
- * @param {!string} newValue The new validated value of the field.
+ * @param {string} newValue The new validated value of the field.
  * @protected
  */
 Blockly.FieldTextInput.prototype.doValueUpdate_ = function(newValue) {
diff --git a/core/flyout_base.js b/core/flyout_base.js
index e42798284..b92c6bcf8 100644
--- a/core/flyout_base.js
+++ b/core/flyout_base.js
@@ -608,7 +608,7 @@ Blockly.Flyout.prototype.onMouseDown_ = function(e) {
  * Does this flyout allow you to create a new instance of the given block?
  * Used for deciding if a block can be "dragged out of" the flyout.
  * @param {!Blockly.BlockSvg} block The block to copy from the flyout.
- * @return {!boolean} True if you can create a new instance of the block, false
+ * @return {boolean} True if you can create a new instance of the block, false
  *    otherwise.
  * @package
  */
diff --git a/core/options.js b/core/options.js
index 9c71541f4..3775f2dcb 100644
--- a/core/options.js
+++ b/core/options.js
@@ -164,7 +164,7 @@ Blockly.Options.prototype.getMetrics = null;
  * Parse the user-specified move options, using reasonable defaults where
  *    behaviour is unspecified.
  * @param {!Object} options Dictionary of options.
- * @param {!boolean} hasCategories Whether the workspace has categories or not.
+ * @param {boolean} hasCategories Whether the workspace has categories or not.
  * @return {!Object} A dictionary of normalized options.
  * @private
  */
diff --git a/core/utils/coordinate.js b/core/utils/coordinate.js
index 7d08362d3..21d6ca50f 100644
--- a/core/utils/coordinate.js
+++ b/core/utils/coordinate.js
@@ -94,8 +94,8 @@ Blockly.utils.Coordinate.magnitude = function(a) {
 /**
  * Returns the difference between two coordinates as a new
  * Blockly.utils.Coordinate.
- * @param {!Blockly.utils.Coordinate} a A Coordinate.
- * @param {!Blockly.utils.Coordinate} b A Coordinate.
+ * @param {!Blockly.utils.Coordinate|!SVGPoint} a An x/y coordinate.
+ * @param {!Blockly.utils.Coordinate|!SVGPoint} b An x/y coordinate.
  * @return {!Blockly.utils.Coordinate} A Coordinate representing the difference
  *     between `a` and `b`.
  */
@@ -105,10 +105,10 @@ Blockly.utils.Coordinate.difference = function(a, b) {
 
 /**
  * Returns the sum of two coordinates as a new Blockly.utils.Coordinate.
- * @param {!Blockly.utils.Coordinate} a A Coordinate.
- * @param {!Blockly.utils.Coordinate} b A Coordinate.
- * @return {!Blockly.utils.Coordinate} A Coordinate representing the sum of the two
- *     coordinates.
+ * @param {!Blockly.utils.Coordinate|!SVGPoint} a An x/y coordinate.
+ * @param {!Blockly.utils.Coordinate|!SVGPoint} b An x/y coordinate.
+ * @return {!Blockly.utils.Coordinate} A Coordinate representing the sum of
+ *     the two coordinates.
  */
 Blockly.utils.Coordinate.sum = function(a, b) {
   return new Blockly.utils.Coordinate(a.x + b.x, a.y + b.y);
diff --git a/core/workspace_svg.js b/core/workspace_svg.js
index 52f7dae05..5fd0c8899 100644
--- a/core/workspace_svg.js
+++ b/core/workspace_svg.js
@@ -1676,7 +1676,7 @@ Blockly.WorkspaceSvg.prototype.zoom = function(x, y, amount) {
   // Find the new scrollX/scrollY so that the center remains in the same
   // position (relative to the center) after we zoom.
   // newScale and matrix.a should be identical (within a rounding error).
-  var matrix = matrix.translate(x * (1 - scaleChange), y * (1 - scaleChange))
+  matrix = matrix.translate(x * (1 - scaleChange), y * (1 - scaleChange))
       .scale(scaleChange);
   // scrollX and scrollY are in pixels.
   // The scrollX and scrollY still need to have absoluteLeft and absoluteTop