Back out changeset aa4791e4dad9 (Bug 529386 - optimize canvas.width = canvas.width) to fix orange.

content/canvas/src/nsCanvasRenderingContext2D.cpp

@@ -842,10 +842,6 @@ nsCanvasRenderingContext2D::Redraw(const gfxRect& r)
 NS_IMETHODIMP
 nsCanvasRenderingContext2D::SetDimensions(PRInt32 width, PRInt32 height)
 {
-    // Avoid creating a new surface if the dimensions are not changing
-    if (mWidth == width && mHeight == height)
-        return InitializeWithSurface(NULL, mSurface, width, height);
-
     Destroy();
 
     nsRefPtr<gfxASurface> surface;
@@ -868,6 +864,8 @@ nsCanvasRenderingContext2D::SetDimensions(PRInt32 width, PRInt32 height)
 
 NS_IMETHODIMP
 nsCanvasRenderingContext2D::InitializeWithSurface(nsIDocShell *docShell, gfxASurface *surface, PRInt32 width, PRInt32 height) {
+    Destroy();
+
     NS_ASSERTION(!docShell ^ !mCanvasElement, "Cannot set both docshell and canvas element");
     mDocShell = docShell;