Ignore mouseup at end of drag with isDragging (#416)

This includes both block drags and workspace scrolls and fixes #404. I
used isDragging rather than checking the origin of click so that it can
easily be extended to the case where the flyout is scrolled by dragging
a block, a la LLK/scratch-blocks#206.

core/field.js

@@ -433,7 +433,7 @@ Blockly.Field.prototype.onMouseUp_ = function(e) {
   } else if (Blockly.isRightButton(e)) {
     // Right-click.
     return;
-  } else if (Blockly.dragMode_ == Blockly.DRAG_FREE) {
+  } else if (this.sourceBlock_.workspace.isDragging()) {
     // Drag operation is concluding.  Don't open the editor.
     return;
   } else if (this.sourceBlock_.isEditable()) {

core/flyout.js

@@ -761,8 +761,7 @@ Blockly.Flyout.prototype.onMouseDown_ = function(e) {
  * @private
  */
 Blockly.Flyout.prototype.onMouseUp_ = function(e) {
-  if (Blockly.dragMode_ != Blockly.DRAG_FREE &&
-      !Blockly.WidgetDiv.isVisible()) {
+  if (!this.workspace_.isDragging() && !Blockly.WidgetDiv.isVisible()) {
     Blockly.Events.fire(
         new Blockly.Events.Ui(Blockly.Flyout.startBlock_, 'click',
                               undefined, undefined));

core/icon.js

@@ -124,7 +124,7 @@ Blockly.Icon.prototype.isVisible = function() {
  * @private
  */
 Blockly.Icon.prototype.iconClick_ = function(e) {
-  if (Blockly.dragMode_ == Blockly.DRAG_FREE) {
+  if (this.block_.workspace.isDragging()) {
     // Drag operation is concluding.  Don't open the editor.
     return;
   }

core/workspace_svg.js

@@ -710,6 +710,14 @@ Blockly.WorkspaceSvg.prototype.moveDrag = function(e) {
   return goog.math.Coordinate.sum(this.dragDeltaXY_, point);
 };
 
+/**
+ * Is the user currently dragging a block or scrolling the workspace?
+ * @return {boolean} True if currently dragging or scrolling
+ */
+Blockly.WorkspaceSvg.prototype.isDragging = function() {
+  return Blockly.dragMode_ == Blockly.DRAG_FREE || this.isScrolling;
+};
+
 /**
  * Handle a mouse-wheel on SVG drawing surface.
  * @param {!Event} e Mouse wheel event.