Bug 920397 part 1 - base::CloseProcessHandle() checks result in debug builds and is used everywhere a process handle is closed.  r=bsmedberg
Bug 920397 part 2 - MessageChannel::~MessageChannel() now asserts that closing the handle succeeded.  r=bsmedberg
Bug 920397 part 3 - Ensure PContentParent doesn't close process handles multiple times.  r=bsmedberg
Bug 783914 - WEBGL_depth_texture doesn't work using ANGLE - r=jgilbert