Merge 128999 - Do touch adjustment on GestureTapDown

LayoutTests/touchadjustment/resources/touchadjustment.js

 /* function for finding the absolute bounds of a node */
 function findAbsoluteBounds(node)
 {
     var bounds = {left: 0, top: 0};
     bounds.width = node.clientWidth;
     bounds.height = node.clientHeight;
     do {
         bounds.left += node.offsetLeft;
         bounds.top += node.offsetTop;
     } while (node = node.offsetParent);
@@ skipping 78 matching lines @@
 function adjustTouchPointContextMenu(touchpoint)
 {
     var adjustedPoint = internals.touchPositionAdjustedToBestContextMenuNode(touchpoint.left, touchpoint.top, touchpoint.width, touchpoint.height, document);
     return adjustedPoint;
 }
 
 function touchPoint(x, y, radiusX, radiusY)
 {
     if (!radiusY)
         radiusY = radiusX;
-    var touchpoint = new Object();
-    touchpoint.left = x - radiusX;
-    touchpoint.top = y - radiusY;
-    touchpoint.width = radiusX * 2;
-    touchpoint.height = radiusY * 2;
-    return touchpoint;
+
+    return {
+        left: x - radiusX,
+        top: y - radiusY,
+        width: radiusX * 2,
+        height: radiusY * 2,
+        get x() { return this.left + this.width/2; },
+        get y() { return this.top + this.height/2; }
+    };
 }
 
 function offsetTouchPoint(bounds, relativePosition, touchOffset, touchRadiusX, touchRadiusY)
 {
     if (!touchRadiusY)
         touchRadiusY = touchRadiusX;
 
-    var touchpoint = {left : bounds.left, top: bounds.top };
+    // Start with the center of the touch at the top-left of the bounds.
+    var touchpoint = touchPoint(bounds.left, bounds.top, touchRadiusX, touchRadiusY);
  
-    // Set center point for touch.
+    // Adjust the touch point as requested.
     switch (relativePosition) {
     case 'center':
         touchpoint.left += bounds.width / 2;
         touchpoint.top += bounds.height / 2;
         break;
     case 'left':
         touchpoint.left -= touchOffset;
         touchpoint.top += bounds.height / 2;
         break;
     case 'right':
@@ skipping 17 matching lines @@
         touchpoint.top += bounds.height + touchOffset;
         break;
     case 'top':
         touchpoint.left += bounds.width / 2;
         touchpoint.top -= touchOffset;
         break;
     case 'bottom':
         touchpoint.left += bounds.width / 2;
         touchpoint.top += bounds.height + touchOffset;
     }
-    // Adjust from touch center to top-left corner.
-    touchpoint.left -= touchRadiusX;
-    touchpoint.top -= touchRadiusY;
-
-    touchpoint.width = 2 * touchRadiusX;
-    touchpoint.height = 2 * touchRadiusY;
 
     return touchpoint;
 }