[New Multicolumn] Guard against zero or negative space shortage.

We need positive values in order to get anywhere when stretching columns
in order to balance them, and we may get called with zero or negative
values when there's zero-height content at column boundaries, or when we
set an early break in order to honor widows in the next column.

BUG=369985

Review URL: https://codereview.chromium.org/263203003

git-svn-id: svn://svn.chromium.org/blink/trunk@174088 bbb929c8-8fbe-4397-9dbb-9b2b20218538
TimelinePanel: apply warning to the entry for JSFrame if it has deoptReason

Drive by fix: do not process CloseFrame for gc events.

BUG=373767

Review URL: https://codereview.chromium.org/282243002

git-svn-id: svn://svn.chromium.org/blink/trunk@174090 bbb929c8-8fbe-4397-9dbb-9b2b20218538
FlameChart: replace entryOffsets with entryStartTimes

BUG=372190

Review URL: https://codereview.chromium.org/283333003

git-svn-id: svn://svn.chromium.org/blink/trunk@174093 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Support warning decorations in Timeline flame chart based on trace events

BUG=361045

Review URL: https://codereview.chromium.org/286123002

git-svn-id: svn://svn.chromium.org/blink/trunk@174094 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Make pseudo-classes selector queries work on DocumentFragment

Make pseudo-classes selector queries work on DocumentFragment as well. This CL
extends tasak@'s r167322 to cover all DocumentFragment nodes, and not only the
ShadowRoot. This was made easier by esprehn@'s r169787 which made the
corresponding code more shareable.

The new behavior is consistent with Firefox 28.

R=esprehn@chromium.org, dglazkov@chromium.org
BUG=355386
TEST=fast/dom/DocumentFragment/sibling-rules-under-document-fragment.html

Review URL: https://codereview.chromium.org/270503006

git-svn-id: svn://svn.chromium.org/blink/trunk@174095 bbb929c8-8fbe-4397-9dbb-9b2b20218538