[Temp] [Android] A temporary way to enable WebGL for Android port.

This is a workaround because some platforms do not support the
GL extension 'GL_{ARB,EXT}_robustness' and the reset notification.
But the pass rate is pretty good for IA platforms. Suggest to
enable WebGL. Do it by using '--ignore-gpu-blacklist' because
it'll bypass this kind of checking.

BUG=#831
Bump version to 2.31.15.0
[BuildFix] Add an explicit dependency on webkit_support.gyp:glue_child

This fix is to add an explicit dependency on webkit_support.gyp:`glue_child` to
`xwalk_runtime` target, otherwise, xwalk will throw an error message
saying 'HeapProfilerStart symbol is not found' at runtime.

BUG=https://github.com/crosswalk-project/crosswalk/issues/859
Merge pull request #845 from yongsheng/webgl

[Android] Enable WebGL for Android port.
Merge pull request #870 from hmin/build-fix

[BuildFix] Add an explicit dependency on webkit_support.gyp:glue_child
WIP: Lazy loader, runner on demand