Revert https://codereview.chromium.org/1078093002/ and follow-on parser
patches due to a perf regression.

This reverts commit 53ddccfc.
This reverts commit 71d3213a.
This reverts commit 0f432ebb.
This reverts commit 1dbc4327.

R=marja@chromium.org

Review URL: https://codereview.chromium.org/1094653002

Cr-Commit-Position: refs/heads/master@{#27912}