The HTML parser should lazy attach.

The rebaselines are one of the following:
-empty whitespace text node changes
-changes in anonymous wrapper blocks that don't affect the resulting layout
-existing race conditions that are exposed by lazy attaching. These are the ones we've deemed OK to land.

Some detailed explanations:
-fast/dom/tabindex-defaults.html: FAIL is because of FIXME inside HTMLElement::supportsFocus crbug.com/285335
-svg/custom/getsvgdocument.html: crbug.com/284734

BUG=276689

Review URL: https://chromiumcodereview.appspot.com/23475019

git-svn-id: svn://svn.chromium.org/blink/trunk@157319 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Remove unused releaseBuffer from Vector.

This is a subset of previously reviewed CL,
https://codereview.chromium.org/23531010/ that had to be reverted due to
unknown reasons for a performance regression. Hence, relanding in pieces.

R=abarth@chromium.org, tsepez@chromium.org

Review URL: https://codereview.chromium.org/23551009

git-svn-id: svn://svn.chromium.org/blink/trunk@157320 bbb929c8-8fbe-4397-9dbb-9b2b20218538