DO NOT MERGE: Apply upstream Chromium patch for encoding changes

Give up looking up interned names if the encoding changed during parsing

NEXTL may process encoding changes by refilling the parser's input
buffer, which makes the accumulated length 'len' inaccurate.

Chromium bug: http://crbug.com/620679

Review-Url: https://codereview.chromium.org/2603933002
Cr-Commit-Position: refs/heads/master@{#442517}

Bug: 36553781
Change-Id: Id3484fbee201d1e19b684b109009d6590354b1d9