Re-land "Don't copy the initiator during preload""

My speculative fix for the perf regression in parser/html-parser was incorrect.
Re-landing Adam's change originally committed in r155802.

BUG=273219
TBR=abarth

Review URL: https://chromiumcodereview.appspot.com/22831007

git-svn-id: svn://svn.chromium.org/blink/trunk@156163 bbb929c8-8fbe-4397-9dbb-9b2b20218538