Unreviewed, rolling back in r190450

Unreviewed, rolling back in r190450
https://bugs.webkit.org/show_bug.cgi?id=149727

This time for sure?

The cause of the leak was an invalidated compilation.

There was vestigial manual memory management code that eagerly removed
a CodeBlock from the set of CodeBlocks if compilation was invalidated.
That's not cool since we rely on the set of CodeBlocks when we run
destructors.

The fix is to remove the vestigial code.

I ran the leaks, correctness, and performance tests locally and did not
see any problems.

Restored changesets:

"CodeBlock should be a GC object"
https://bugs.webkit.org/show_bug.cgi?id=149727
http://trac.webkit.org/changeset/190450

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@190694 268f45cc-cd09-0410-ab3c-d52691b4dbfc