Correct Rendering for Block Images After Resize Undo

If a block image is resized and undone, there are lots of problems.

* The block image gets the wrong size. When rolling back the
transaction, height and width are passed as strings.
MWBlockImage tries to set the width to: width + 2. A 300px image
became 3002px.

* Resize handles didn't reposition and resize

* Relocatable drag marker didn't reposition and resize

* Focusable highlights didn't reposition and resize.

Change-Id: I8792b567b77da90ce5a2ad132e306705c5706606