GitLab

When an element's renderer is being reattached, previously we reattach
whitespace siblings, causing full paint invalidation of the parent.

If the whitespace sibling needed renderer and still needs renderer,
don't reattach.

- Renamed Node::reattachWhitespaceSiblings() to
  Node::reattachWhitespaceSlibingsIfNeeded();
- In the function, test if rendererIsNeeded changed before reattaching;
- Modified Text::textRendererIsNeeded() so that it can return correct
  value when the Text has already renderer.

BUG=428997
TEST=fast/repaint/absolute-display-block-to-none.html
TEST=fast/forms/select-listbox-focus-displaynone.html (Existing test
covering the change in Text.cpp).

Review URL: https://codereview.chromium.org/684633006

git-svn-id: svn://svn.chromium.org/blink/trunk@185421 bbb929c8-8fbe-4397-9dbb-9b2b20218538