Rollback of r12341, r12342, r12343, r12344, r12345, r12347 in trunk branch.

Rollback of r12341, r12342, r12343, r12344, r12345, r12347 in trunk branch.

Rename JSGlobalProxy::context to native_context, for clarity and consistency with GlobalObject::native_context.

Flush monomorphic ICs on context disposal instead of context exit.

Fix test failures introduced by r12342.

Handle native callbacks without getters.

While allocating code objects, perform the incremental marking step before NULLing the new object. Otherwise the code cache cannot iterate the code space anymore, which is required to clear ICs.

Fix mjsunit/debug-script.js failure that occurs when running with the --isolates flag.

R=vegorov@chromium.org
BUG=