Move property setting/removing/addParsedProperty/addParsedProperties functions to MutableStylePrope…

Move property setting/removing/addParsedProperty/addParsedProperties functions to MutableStylePropertySet.

Move all functions for setting/removing properties from StylePropertySet to MutableStylePropertySet.
Had to change SVGElement::animatedSMILStyleProperties() & friends to hand out MutableStylePropertySet*
which was always the internal type anyway.

Switch EditingStyle::m_mutableStyle to a RefPtr<MutableStylePropertySet>.

This is a backport from WebKit r148400, r148402, 148403. Patches by Andreas Kling reviewed by Anders Carlsson and Antti Koivisto.

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=151189

[darktears, 2013-05-24 20:49:17]

There will be just one more and we're done with this refactor (I'll do it on
Monday). Thanks eric for the reviews.

[apavlov, 2013-05-27 07:13:02]

lgtm

[commit-bot: I haz the power, 2013-05-27 11:22:37]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/alexis.menard@intel.com/15821009/1

[commit-bot: I haz the power, 2013-05-27 11:25:24]

Change committed as 151189