Land hash collision fix for V8 3.6 by Erik Corry.

- If V8 snapshots are enabled then the hash is only randomized at build time.
- Breaks MIPS

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Backport hash collision workaround to 3.6.
This is made up of 9956, 10351, 10338 and 10330.
This change bakes the string hash key into the snapshot, so
it is determined at build time for shapshot configs.
Review URL: http://codereview.chromium.org/9124004