Revert 247589 "<webview>: Fix text selection features in mac."

Revert 247589 "<webview>: Fix text selection features in mac."

> <webview>: Fix text selection features in mac.
> We still need to pass RWHVGuest::SelectionChanged() call to platform_view_.
> This broke while adding IME support, this function doesn't seem to be required for IME (made sure by running BrowserPluginHostTest.InputMethod).
> 
> Wrote a browser_test to catch the regression.
> 
> BUG=331722
> Test=Open a <webview> in a chrome app. Select some text. Observe that "Look up in dictionary" and "Speech=>Start Speaking" features work.
> 
> Review URL: https://codereview.chromium.org/148433007

Suspected of causing flakes in

WithoutThreadedCompositor/WebViewCaptureTest.Shim_ScreenshotCapture , see

http://build.chromium.org/p/chromium.webkit/builders/Mac10.8%20Tests/builds/5692
and
http://build.chromium.org/p/chromium.webkit/builders/Win7%20Tests/builds/928

TBR=lazyboy@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=247722

[gavinp, 2014-01-29 18:21:17]

Committed patchset #1 manually as r247722.

[lazyboy, 2014-01-30 16:48:35]

On 2014/01/29 18:21:17, gavinp wrote:
> Committed patchset #1 manually as r247722.

Can we revert this?
Flake cause for
WithoutThreadedCompositor/WebViewCaptureTest.Shim_ScreenshotCapture is
unrelated, the test was disabled in crbug.com/339271