[Reland] WEBPImageDecoder: Fix for ASSERTION FAILED:
width== frameRect.width()

If all data of a frame is received, but WebPIUpdate returns
VP8_STATUS_SUSPENDED, then it's an invalid image.

Patch is same as earlier.
The fix http://crrev.com/53143006 would make this work on all platforms.

BUG=310259

Review URL: https://codereview.chromium.org/50533009

git-svn-id: svn://svn.chromium.org/blink/trunk@161036 bbb929c8-8fbe-4397-9dbb-9b2b20218538