Revert "WebVR: Update VRDisplay.GetFrameData to follow the current spec."

This reverts commit 14020f57ee8a8bc8cce58c3fc694cfc00c2d0467.

Reason for revert: Hold off on API breaking change till M62, so we can have several that go out at the same time and we'll have a new origin trial.

Original change's description:
> WebVR: Update VRDisplay.GetFrameData to follow the current spec.
> 
> The WebVR 1.1 spec was updated to clarify the behavior of getFrameData.
> Now, GetFrameData should return false unless called within a
> VRDisplay.requestAnimationFrame callback.
> 
> BUG=736023
> 
> Change-Id: I14d9442a016817a78232ed7b1e71956c8dac614a
> Reviewed-on: https://chromium-review.googlesource.com/578188
> Reviewed-by: Brandon Jones <bajones@chromium.org>
> Commit-Queue: Bill Orr <billorr@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#487970}

TBR=bajones@chromium.org,bsheedy@chromium.org,billorr@chromium.org

Change-Id: Ia0491a7af887c6149b69178747f6a0e6a9b5f3d2
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 736023
Reviewed-on: https://chromium-review.googlesource.com/580167
Reviewed-by: Michael Thiessen <mthiesse@chromium.org>
Commit-Queue: Michael Thiessen <mthiesse@chromium.org>
Cr-Commit-Position: refs/heads/master@{#488396}
2 files changed