Currently, V8 uses the same size counter to measure the minimum number of memory pages allocated by a module for both asm.js and WASM. This CL separates the counter into two separate counters, and then uses the appropriate counter when measuring.

BUG=chromium:704922
R=mtrofin@chromium.org,bradnelson@chromium.org

Review-Url: https://codereview.chromium.org/2781453004
Cr-Commit-Position: refs/heads/master@{#44204}