Update to Chromium revision 272007.
- Remove CefSettings.accelerated_compositing option (see https://crbug.com/363772).
- Remove experimental x-webkit-speech support (see https://crbug.com/223198).
- Execute CefGeolocationHandler callbacks on the UI thread (see https://crbug.com/304341#c212).

git-svn-id: http://chromiumembedded.googlecode.com/svn/trunk/cef3@1711 5089003a-bbd8-11dd-ad1f-f1f9622dbc98
Change CefV8ValueImpl::Handle lifespan so that persistent V8 handles can be reset after execution of the weak persistent destructor. The previous implementation reset persistent V8 handles immediately after calling SetWeak which caused a memory leak due to the weak persistent destructor never being executed (issue #1278).

git-svn-id: http://chromiumembedded.googlecode.com/svn/trunk/cef3@1712 5089003a-bbd8-11dd-ad1f-f1f9622dbc98