Mark some classes STACK_ALLOCATED.

Marking a class stack allocated allows an object to have pointers to GC managed objects without wrapping them in Member and defining a trace method to trace them. The Blink GC plugin for clang will identify the marked object as stack allocated and check it accordingly.

Review URL: https://codereview.chromium.org/163593003

git-svn-id: svn://svn.chromium.org/blink/trunk@167781 bbb929c8-8fbe-4397-9dbb-9b2b20218538