Avoid calculating style for ::before/::after without content.

A universal ::before or ::after rule without content triggers calculation
of pseudo style for most elements on theverge.com just to find that most of
them won't be rendered due to the missing content.

Check if matching ::before or ::after rules actually contain a content
value before marking the render style with setHasPseudoStyle.

This change reduces the style recalc time by ~50% when expanding the
comments section on theverge.com articles.

R=esprehn@chromium.org,eseidel@chromium.org
BUG=412558

Review URL: https://codereview.chromium.org/570713002

git-svn-id: svn://svn.chromium.org/blink/trunk@182308 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Should protect document in ProcessingInstruction::setXSLStyleSheet.

BUG=403276

Review URL: https://codereview.chromium.org/579133004

git-svn-id: svn://svn.chromium.org/blink/trunk@182309 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Bring back mac expectation for inline-before-content-after-list-marker-expected

...remove mac-snowleopard as originally intended.

TBR=wangxianzhu@chromium.org

Review URL: https://codereview.chromium.org/581223003

git-svn-id: svn://svn.chromium.org/blink/trunk@182310 bbb929c8-8fbe-4397-9dbb-9b2b20218538
[SVG] Restore the non-selection style after painting the selected run

After having painted the selection-styled text run, the resources need to
be re-acquired with the non-selection style.

BUG=415632

Review URL: https://codereview.chromium.org/585563002

git-svn-id: svn://svn.chromium.org/blink/trunk@182311 bbb929c8-8fbe-4397-9dbb-9b2b20218538