Bug 852620 - Rename nsSVGRect to SVGRect, r=Ms2ger

--HG--
rename : content/svg/content/src/nsSVGRect.cpp => content/svg/content/src/SVGRect.cpp
rename : content/svg/content/src/nsSVGRect.h => content/svg/content/src/SVGRect.h
Bug 852620 - Convert SVGRect to WebIDL, r=Ms2ger