diff --git a/core/block_svg.js b/core/block_svg.js
index 347a56be7..c340576be 100644
--- a/core/block_svg.js
+++ b/core/block_svg.js
@@ -40,6 +40,7 @@ goog.require('Blockly.Touch');
 goog.require('Blockly.utils');
 goog.require('Blockly.utils.Coordinate');
 goog.require('Blockly.utils.dom');
+goog.require('Blockly.utils.Rect');
 
 
 /**
@@ -469,8 +470,7 @@ Blockly.BlockSvg.prototype.snapToGrid = function() {
  * Returns the coordinates of a bounding box describing the dimensions of this
  * block and any blocks stacked below it.
  * Coordinate system: workspace coordinates.
- * @return {!{top: number, bottom: number, left: number, right: number}}
- *    Object with top, bottom, left, and right coordinates of the bounding box.
+ * @return {!Blockly.utils.Rect} Object with coordinates of the bounding box.
  */
 Blockly.BlockSvg.prototype.getBoundingRectangle = function() {
   var blockXY = this.getRelativeToSurfaceXY(this);
@@ -492,7 +492,7 @@ Blockly.BlockSvg.prototype.getBoundingRectangle = function() {
     // Width has the tab built into it already so subtract it here.
     right = blockXY.x + blockBounds.width - tab;
   }
-  return {top: top, bottom: bottom, left: left, right: right};
+  return new Blockly.utils.Rect(top, bottom, left, right);
 };
 
 /**
diff --git a/core/inject.js b/core/inject.js
index e40d110e5..5d4aa5545 100644
--- a/core/inject.js
+++ b/core/inject.js
@@ -312,8 +312,7 @@ Blockly.createMainWorkspace_ = function(svg, options, blockDragSurface,
             }
 
             // Bump any object that's below the bottom back inside.
-            var overflowBottom =
-                metrics.viewBottom - objectMetrics.bottom;
+            var overflowBottom = metrics.viewBottom - objectMetrics.bottom;
             if (overflowBottom < 0) {
               object.moveBy(0, overflowBottom);
             }
diff --git a/core/workspace_comment_svg.js b/core/workspace_comment_svg.js
index 3469c1deb..b93331c6a 100644
--- a/core/workspace_comment_svg.js
+++ b/core/workspace_comment_svg.js
@@ -34,6 +34,7 @@ goog.require('Blockly.Events.Ui');
 goog.require('Blockly.utils');
 goog.require('Blockly.utils.Coordinate');
 goog.require('Blockly.utils.dom');
+goog.require('Blockly.utils.Rect');
 goog.require('Blockly.WorkspaceComment');
 
 
@@ -419,8 +420,7 @@ Blockly.WorkspaceCommentSvg.prototype.clearTransformAttributes_ = function() {
  * Returns the coordinates of a bounding box describing the dimensions of this
  * comment.
  * Coordinate system: workspace coordinates.
- * @return {!{top: number, bottom: number, left: number, right: number}}
- *    Object with top, bottom, left, and right coordinates of the bounding box.
+ * @return {!Blockly.utils.Rect} Object with coordinates of the bounding box.
  * @package
  */
 Blockly.WorkspaceCommentSvg.prototype.getBoundingRectangle = function() {
@@ -440,7 +440,7 @@ Blockly.WorkspaceCommentSvg.prototype.getBoundingRectangle = function() {
     left = blockXY.x;
     right = blockXY.x + commentBounds.width;
   }
-  return {top: top, bottom: bottom, left: left, right: right};
+  return new Blockly.utils.Rect(top, bottom, left, right);
 };
 
 /**
diff --git a/core/workspace_svg.js b/core/workspace_svg.js
index bcbe72918..7cedea7ee 100644
--- a/core/workspace_svg.js
+++ b/core/workspace_svg.js
@@ -43,6 +43,7 @@ goog.require('Blockly.Trashcan');
 goog.require('Blockly.utils');
 goog.require('Blockly.utils.Coordinate');
 goog.require('Blockly.utils.dom');
+goog.require('Blockly.utils.Rect');
 goog.require('Blockly.VariablesDynamic');
 goog.require('Blockly.Workspace');
 goog.require('Blockly.WorkspaceAudio');
@@ -1352,8 +1353,8 @@ Blockly.WorkspaceSvg.prototype.onMouseWheel_ = function(e) {
  * Calculate the bounding box for the blocks on the workspace.
  * Coordinate system: workspace coordinates.
  *
- * @return {Object} Contains the position and size of the bounding box
- *   containing the blocks on the workspace.
+ * @return {!Blockly.utils.Rect} Contains the position and size of the
+ *   bounding box containing the blocks on the workspace.
  */
 Blockly.WorkspaceSvg.prototype.getBlocksBoundingBox = function() {
   var topBlocks = this.getTopBlocks(false);
@@ -1361,7 +1362,7 @@ Blockly.WorkspaceSvg.prototype.getBlocksBoundingBox = function() {
   var topElements = topBlocks.concat(topComments);
   // There are no blocks, return empty rectangle.
   if (!topElements.length) {
-    return {top: 0, bottom: 0, left: 0, right: 0};
+    return new Blockly.utils.Rect(0, 0, 0, 0);
   }
 
   // Initialize boundary using the first block.
@@ -1370,18 +1371,18 @@ Blockly.WorkspaceSvg.prototype.getBlocksBoundingBox = function() {
   // Start at 1 since the 0th block was used for initialization.
   for (var i = 1; i < topElements.length; i++) {
     var blockBoundary = topElements[i].getBoundingRectangle();
-    if (blockBoundary.left < boundary.left) {
-      boundary.left = blockBoundary.left;
-    }
-    if (blockBoundary.right > boundary.right) {
-      boundary.right = blockBoundary.right;
-    }
     if (blockBoundary.top < boundary.top) {
       boundary.top = blockBoundary.top;
     }
     if (blockBoundary.bottom > boundary.bottom) {
       boundary.bottom = blockBoundary.bottom;
     }
+    if (blockBoundary.left < boundary.left) {
+      boundary.left = blockBoundary.left;
+    }
+    if (blockBoundary.right > boundary.right) {
+      boundary.right = blockBoundary.right;
+    }
   }
   return boundary;
 };