Make MediaList API arguments mandatory

Make MediaList API arguments mandatory to match the specification:
http://www.w3.org/TR/DOM-Level-2-Style/stylesheets.html#StyleSheets-MediaList

This behavior is consistent with Firefox 23 and IE10. It is confusing what
the result is supposed to be when the arguments are omitted.

BUG=

Review URL: https://chromiumcodereview.appspot.com/23621013

git-svn-id: svn://svn.chromium.org/blink/trunk@157063 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Modify StepsTimingFunction to record whether it was created from a preset CSS Value

The CSS3 Animations spec [1] requires that the value returned by
getComputedStyle() for the animation-timing-function property is the specified
value.

Currently, we follow this for all values other than 'step-start' and
'step-end'. In these cases, we represent the values using the 'step()' syntax.
This change fixes these two cases so that getComputedStyle() always return the
specified value.

Note that Firefox does not follow the spec and always returns the values using
the 'step()' or 'cubic-bezier()' syntax.

Also cache a singleton StepsTimingFunction for each of 'step-start' and
'step-end'.

[1] http://dev.w3.org/csswg/css-animations/#animation-timing-function

R=dstockwell

Review URL: https://chromiumcodereview.appspot.com/23442009

git-svn-id: svn://svn.chromium.org/blink/trunk@157064 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Delete ad-hoc console implementation in HeapSnapshotWorker

Now that we have native console for dedicated workers there is no need to keep this custom implementation.

BUG=None
R=vsevik@chromium.org

Review URL: https://codereview.chromium.org/23726010

git-svn-id: svn://svn.chromium.org/blink/trunk@157065 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Make arguments to CSSMediaRule.insertRule() / deleteRule() mandatory

Make arguments to CSSMediaRule.insertRule() / deleteRule() mandatory as per
the specification:
http://www.w3.org/TR/DOM-Level-2-Style/css.html#CSS-CSSMediaRule

This behavior is consistent with Firefox 23 and IE10. It is confusing what
is supposed to happen if the arguments are omitted.

BUG=

Review URL: https://chromiumcodereview.appspot.com/23707008

git-svn-id: svn://svn.chromium.org/blink/trunk@157066 bbb929c8-8fbe-4397-9dbb-9b2b20218538