Fix two memory leaks (#3747)

* Fix two memory leaks

core/block_dragger.js

@@ -291,6 +291,7 @@ Blockly.BlockDragger.prototype.maybeDeleteBlock_ = function() {
     // Fire a move event, so we know where to go back to for an undo.
     this.fireMoveEvent_();
     this.draggingBlock_.dispose(false, true);
+    Blockly.draggingConnections = [];
   } else if (trashcan) {
     // Make sure the trash can is closed.
     trashcan.close();

core/block_svg.js

@@ -943,7 +943,8 @@ Blockly.BlockSvg.prototype.dispose = function(healStack, animate) {
     // The block has already been deleted.
     return;
   }
-  Blockly.Tooltip.hide();
+  Blockly.Tooltip.dispose();
+  Blockly.Tooltip.unbindMouseEvents(this.pathObject.svgPath);
   Blockly.utils.dom.startTextWidthCache();
   // Save the block's workspace temporarily so we can resize the
   // contents once the block is disposed.

core/field.js

@@ -394,6 +394,7 @@ Blockly.Field.prototype.toXml = function(fieldElement) {
 Blockly.Field.prototype.dispose = function() {
   Blockly.DropDownDiv.hideIfOwner(this);
   Blockly.WidgetDiv.hideIfOwner(this);
+  Blockly.Tooltip.unbindMouseEvents(this.getClickTarget_());
 
   if (this.mouseDownWrapper_) {
     Blockly.unbindEvent_(this.mouseDownWrapper_);

core/flyout_base.js

@@ -548,6 +548,7 @@ Blockly.Flyout.prototype.clearOldBlocks_ = function() {
   for (var j = 0; j < this.mats_.length; j++) {
     var rect = this.mats_[j];
     if (rect) {
+      Blockly.Tooltip.unbindMouseEvents(rect);
       Blockly.utils.dom.removeNode(rect);
     }
   }

core/tooltip.js

@@ -129,9 +129,9 @@ Blockly.Tooltip.createDom = function() {
  * @param {!Element} element SVG element onto which tooltip is to be bound.
  */
 Blockly.Tooltip.bindMouseEvents = function(element) {
-  Blockly.bindEvent_(element, 'mouseover', null,
+  element.mouseOverWrapper_ = Blockly.bindEvent_(element, 'mouseover', null,
       Blockly.Tooltip.onMouseOver_);
-  Blockly.bindEvent_(element, 'mouseout', null,
+  element.mouseOutWrapper_ = Blockly.bindEvent_(element, 'mouseout', null,
       Blockly.Tooltip.onMouseOut_);
 
   // Don't use bindEvent_ for mousemove since that would create a
@@ -140,6 +140,19 @@ Blockly.Tooltip.bindMouseEvents = function(element) {
   element.addEventListener('mousemove', Blockly.Tooltip.onMouseMove_, false);
 };
 
+/**
+ * Unbinds tooltip mouse events from the SVG element.
+ * @param {!Element} element SVG element onto which tooltip is bound.
+ */
+Blockly.Tooltip.unbindMouseEvents = function(element) {
+  if (!element) {
+    return;
+  }
+  Blockly.unbindEvent_(element.mouseOverWrapper_);
+  Blockly.unbindEvent_(element.mouseOutWrapper_);
+  element.removeEventListener('mousemove', Blockly.Tooltip.onMouseMove_);
+};
+
 /**
  * Hide the tooltip if the mouse is over a different object.
  * Initialize the tooltip to potentially appear for this object.
@@ -223,6 +236,16 @@ Blockly.Tooltip.onMouseMove_ = function(e) {
   }
 };
 
+/**
+ * Dispose of the tooltip.
+ * @package
+ */
+Blockly.Tooltip.dispose = function() {
+  Blockly.Tooltip.element_ = null;
+  Blockly.Tooltip.poisonedElement_ = null;
+  Blockly.Tooltip.hide();
+};
+
 /**
  * Hide the tooltip.
  */