Improve a search logic to find a SVGFontFaceSrcElement
Improve a search logic to find a SVGFontFaceSrcElement

In SVGFontFaceElement::rebuildFontFace(), it tries to find a SVGFontFaceSrcElement. However, current search logic looks inefficient. The search logic starts to find SVGFontFaceSrcElement from a first child node, then it replaces a discovered element whenever finding next SVGFontFaceSrcElement. Thus, it would be good if we find SVGFontFaceSrcElement from a last node. Then, we go out of the searching loop as soon as we find a first SVGFontFaceSrcElement. It will help to reduce iteration number in the search loop.

Additionally the search loop is moved to the place which uses a SVGFontFaceSrcElement actually.

BUG=N/A

Review URL: https://codereview.chromium.org/133493002

git-svn-id: bf5cd6ccde378db821296732a091cfbcf5285fbd@164881 bbb929c8-8fbe-4397-9dbb-9b2b20218538

modulexcite/blink,XiaosongWei/blink-crosswalk,Pluto-tv/blink-crosswalk,ondra-novak/blink,PeterWangIntel/blink-crosswalk,jtg-gg/blink,PeterWangIntel/blink-crosswalk,PeterWangIntel/blink-crosswalk,PeterWangIntel/blink-crosswalk,XiaosongWei/blink-crosswalk,Pluto-tv/blink-crosswalk,crosswalk-project/blink-crosswalk-efl,Bysmyyr/blink-crosswalk,ondra-novak/blink,PeterWangIntel/blink-crosswalk,smishenk/blink-crosswalk,smishenk/blink-crosswalk,ondra-novak/blink,modulexcite/blink,Bysmyyr/blink-crosswalk,hgl888/blink-crosswalk-efl,hgl888/blink-crosswalk-efl,ondra-novak/blink,kurli/blink-crosswalk,hgl888/blink-crosswalk-efl,hgl888/blink-crosswalk-efl,ondra-novak/blink,crosswalk-project/blink-crosswalk-efl,Bysmyyr/blink-crosswalk,smishenk/blink-crosswalk,modulexcite/blink,Pluto-tv/blink-crosswalk,jtg-gg/blink,smishenk/blink-crosswalk,nwjs/blink,crosswalk-project/blink-crosswalk-efl,nwjs/blink,smishenk/blink-crosswalk,kurli/blink-crosswalk,modulexcite/blink,XiaosongWei/blink-crosswalk,jtg-gg/blink,modulexcite/blink,XiaosongWei/blink-crosswalk,kurli/blink-crosswalk,ondra-novak/blink,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,crosswalk-project/blink-crosswalk-efl,PeterWangIntel/blink-crosswalk,jtg-gg/blink,XiaosongWei/blink-crosswalk,PeterWangIntel/blink-crosswalk,jtg-gg/blink,modulexcite/blink,ondra-novak/blink,Bysmyyr/blink-crosswalk,XiaosongWei/blink-crosswalk,smishenk/blink-crosswalk,jtg-gg/blink,Pluto-tv/blink-crosswalk,crosswalk-project/blink-crosswalk-efl,ondra-novak/blink,modulexcite/blink,kurli/blink-crosswalk,smishenk/blink-crosswalk,Pluto-tv/blink-crosswalk,nwjs/blink,hgl888/blink-crosswalk-efl,kurli/blink-crosswalk,kurli/blink-crosswalk,kurli/blink-crosswalk,Bysmyyr/blink-crosswalk,nwjs/blink,nwjs/blink,Pluto-tv/blink-crosswalk,XiaosongWei/blink-crosswalk,smishenk/blink-crosswalk,nwjs/blink,nwjs/blink,Pluto-tv/blink-crosswalk,modulexcite/blink,modulexcite/blink,jtg-gg/blink,hgl888/blink-crosswalk-efl,Bysmyyr/blink-crosswalk,crosswalk-project/blink-crosswalk-efl,kurli/blink-crosswalk,kurli/blink-crosswalk,nwjs/blink,PeterWangIntel/blink-crosswalk,Bysmyyr/blink-crosswalk,crosswalk-project/blink-crosswalk-efl,crosswalk-project/blink-crosswalk-efl,kurli/blink-crosswalk,XiaosongWei/blink-crosswalk,hgl888/blink-crosswalk-efl,ondra-novak/blink,jtg-gg/blink,nwjs/blink,hgl888/blink-crosswalk-efl,hgl888/blink-crosswalk-efl,smishenk/blink-crosswalk,jtg-gg/blink,modulexcite/blink,crosswalk-project/blink-crosswalk-efl,Bysmyyr/blink-crosswalk,PeterWangIntel/blink-crosswalk,hgl888/blink-crosswalk-efl,XiaosongWei/blink-crosswalk,Bysmyyr/blink-crosswalk,jtg-gg/blink,XiaosongWei/blink-crosswalk,Bysmyyr/blink-crosswalk,Pluto-tv/blink-crosswalk,nwjs/blink,PeterWangIntel/blink-crosswalk,smishenk/blink-crosswalk