commit 0f3eb18441ba1c98a8bb7ef8d482b22f682c6968
author xidachen <xidachen@chromium.org> Mon Dec 14 20:57:51 2015
committer Commit bot <commit-bot@chromium.org> Mon Dec 14 20:59:18 2015
tree fa3fb4ecc90788d0ce59f2617dbe4dc792577614
parent 5f0ad43b809bd1e8f265cb47a6d7fa0853d5106e

Create an empty interface OffScreenCanvas

This CL creates an interface OffScreenCanvas.idl according to the proposal:
https://wiki.whatwg.org/wiki/OffscreenCanvas

At this moment, the interface only has a constructor, and its implementation is empty.

Also, a layout test is added to verify that the constructor
can be successfully called from JS, and verify the object's
width&height, together with verifying the constructor's behavior when
the argument is invalid.

BUG=563819

Review URL: https://codereview.chromium.org/1488763002

Cr-Commit-Position: refs/heads/master@{#365095}