Fixed type annotations on namespaces.

More information:
    https://github.com/google/closure-compiler/wiki/A-word-about-the-type-Object
Added v8::Platform initialization, required by v8 3.29.

I don't actually have a version of v8 3.29 installed on my workstation
to test with for the open source release, so doing this commit on a
branch to start with. It is necessary for use with the Google-internal
version.
Added two missing includes for v8's libplatform.h.