Merge pull request #438 from rachel-fenichel/feature/cache_delete_areas

Cache delete areas

core/block_svg.js

@@ -535,7 +535,6 @@ Blockly.BlockSvg.prototype.onMouseDown_ = function(e) {
   Blockly.terminateDrag_();
   this.select();
   Blockly.hideChaff();
-  this.workspace.recordDeleteAreas();
   if (Blockly.isRightButton(e)) {
     // Right-click.
     this.showContextMenu_(e);

core/flyout.js

@@ -952,6 +952,10 @@ Blockly.Flyout.prototype.filterForCapacity_ = function() {
  * @return {goog.math.Rect} Rectangle in which to delete.
  */
 Blockly.Flyout.prototype.getClientRect = function() {
+  if (!this.svgGroup_) {
+    return null;
+  }
+
   var flyoutRect = this.svgGroup_.getBoundingClientRect();
   // BIG_NUM is offscreen padding so that blocks dragged beyond the shown flyout
   // area are still deleted.  Must be larger than the largest screen size,

core/toolbox.js

@@ -390,6 +390,10 @@ Blockly.Toolbox.prototype.clearSelection = function() {
  * @return {goog.math.Rect} Rectangle in which to delete.
  */
 Blockly.Toolbox.prototype.getClientRect = function() {
+  if (!this.HtmlDiv) {
+    return null;
+  }
+
   // BIG_NUM is offscreen padding so that blocks dragged beyond the toolbox
   // area are still deleted.  Must be smaller than Infinity, but larger than
   // the largest screen size.

core/trashcan.js

@@ -265,6 +265,10 @@ Blockly.Trashcan.prototype.position = function() {
  * @return {goog.math.Rect} Rectangle in which to delete.
  */
 Blockly.Trashcan.prototype.getClientRect = function() {
+  if (!this.svgGroup_) {
+    return null;
+  }
+
   var trashRect = this.svgGroup_.getBoundingClientRect();
   var left = trashRect.left + this.SPRITE_LEFT_ - this.MARGIN_HOTSPOT_;
   var top = trashRect.top + this.SPRITE_TOP_ - this.MARGIN_HOTSPOT_;

core/workspace_svg.js

@@ -211,6 +211,7 @@ Blockly.WorkspaceSvg.prototype.createDom = function(opt_backgroundClass) {
     this.addFlyout_();
   }
   this.updateGridPattern_();
+  this.recordDeleteAreas();
   return this.svgGroup_;
 };
 
@@ -355,6 +356,8 @@ Blockly.WorkspaceSvg.prototype.resize = function() {
   if (this.scrollbar) {
     this.scrollbar.resize();
   }
+
+  this.recordDeleteAreas();
 };
 
 /**