Do not merge DocumentMarkers of type TextMatch.

Markers added to a DocumentMarkerController get merged into a single marker when they overlap or are adjacent to each other. This causes problems for text match markers which can be individually activated, e.g. for stepping through results of a FindInPage operation. This patch fixes this problem by never merging DocumentMarkers of type TextMatch in DocumentMarkerController::addMarker().

BUG=142071

Review URL: https://chromiumcodereview.appspot.com/21372003

git-svn-id: svn://svn.chromium.org/blink/trunk@156293 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Add a LayoutTest for animation iteration events when the duration is short

BUG=275263
R=dstockwell

Review URL: https://chromiumcodereview.appspot.com/22870010

git-svn-id: svn://svn.chromium.org/blink/trunk@156295 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Convert DOMWindow SecurityError exceptions to 'es.throwSecurityError()'.

Eventually, 'throwDOMException' should ASSERT that it's not being used
for 'SecurityError' (as we want callers to think about the security
implication of exposing their message to JavaScript). To do that, we
need to move all current callers over to the new sanitization-capable
API.

BUG=275282

Review URL: https://chromiumcodereview.appspot.com/22903009

git-svn-id: svn://svn.chromium.org/blink/trunk@156296 bbb929c8-8fbe-4397-9dbb-9b2b20218538