- Coalesced all anonymous namespaces into one, and moved it to the
top of the file, to match elsewhere in the v8 codebase.
- Deleted dead code.
- Moved functions that turned out to be local to wasm-module.cc to
the anonymous namespace.

BUG=

Review-Url: https://codereview.chromium.org/2384183002
Cr-Commit-Position: refs/heads/master@{#39936}