Make template scan related function take a template<bool> parameter

This is for performance. Having to do the test in every Advance was too
expensive.

BUG=438991, v8:3230
LOG=N
R=dslomov@chromium.org, marja

Review URL: https://codereview.chromium.org/766193003

Cr-Commit-Position: refs/heads/master@{#25667}
Optimize add/set/delete operations for string keys in Maps and Sets

Review URL: https://codereview.chromium.org/773993002

Cr-Commit-Position: refs/heads/master@{#25668}
Add js-perf-test for ES6 class default constructor

BUG=v8:3330
LOG=N
TBR=dslomov@chromium.org

Review URL: https://codereview.chromium.org/754523004

Cr-Commit-Position: refs/heads/master@{#25669}