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.

Review URL:

git-svn-id: svn:// bbb929c8-8fbe-4397-9dbb-9b2b20218538
12 files changed