Adding timing info going to the console about asm.js

Rename ConvertAsmToWasm -> CompileAsmViaWasm, to be more precise.
Add enum for wasm data elements.

BUG=v8:4203
R=titzer@chromium.org,yangguo@chromium.org

Review-Url: https://codereview.chromium.org/2577453003
Cr-Commit-Position: refs/heads/master@{#41695}