dbus: don't add attributes in extern template class specialization
dbus: don't add attributes in extern template class specialization

This previous CL added attributes to some template specializations:
https://codereview.chromium.org/408143012

This breaks gcc 4.8, which gives the following warning:
  ../../dbus/property.h:412:62: error: type attributes ignored after type is already defined [-Werror=attributes]

Since the template class already has the attribute, I suspect that the
additional attribute specifications are redundant.  ie I think we can
remove them.

Review URL: https://codereview.chromium.org/423233003

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@286567 0039d316-1c4b-4281-b951-d872f2087c98

hgl888/chromium-crosswalk,krieger-od/nwjs_chromium.src,Pluto-tv/chromium-crosswalk,krieger-od/nwjs_chromium.src,M4sse/chromium.src,hgl888/chromium-crosswalk-efl,krieger-od/nwjs_chromium.src,Pluto-tv/chromium-crosswalk,Fireblend/chromium-crosswalk,Pluto-tv/chromium-crosswalk,PeterWangIntel/chromium-crosswalk,ltilve/chromium,fujunwei/chromium-crosswalk,TheTypoMaster/chromium-crosswalk,markYoungH/chromium.src,crosswalk-project/chromium-crosswalk-efl,Jonekee/chromium.src,Jonekee/chromium.src,mohamed--abdel-maksoud/chromium.src,Just-D/chromium-1,markYoungH/chromium.src,TheTypoMaster/chromium-crosswalk,dushu1203/chromium.src,axinging/chromium-crosswalk,Jonekee/chromium.src,markYoungH/chromium.src,Chilledheart/chromium,PeterWangIntel/chromium-crosswalk,ltilve/chromium,mohamed--abdel-maksoud/chromium.src,Pluto-tv/chromium-crosswalk,Pluto-tv/chromium-crosswalk,jaruba/chromium.src,TheTypoMaster/chromium-crosswalk,hgl888/chromium-crosswalk,bright-sparks/chromium-spacewalk,axinging/chromium-crosswalk,Jonekee/chromium.src,Chilledheart/chromium,mohamed--abdel-maksoud/chromium.src,mohamed--abdel-maksoud/chromium.src,bright-sparks/chromium-spacewalk,bright-sparks/chromium-spacewalk,ondra-novak/chromium.src,M4sse/chromium.src,Fireblend/chromium-crosswalk,hgl888/chromium-crosswalk-efl,ondra-novak/chromium.src,hgl888/chromium-crosswalk-efl,Fireblend/chromium-crosswalk,Fireblend/chromium-crosswalk,M4sse/chromium.src,ondra-novak/chromium.src,mohamed--abdel-maksoud/chromium.src,dednal/chromium.src,TheTypoMaster/chromium-crosswalk,dednal/chromium.src,Pluto-tv/chromium-crosswalk,Jonekee/chromium.src,littlstar/chromium.src,markYoungH/chromium.src,hgl888/chromium-crosswalk,Jonekee/chromium.src,PeterWangIntel/chromium-crosswalk,jaruba/chromium.src,hgl888/chromium-crosswalk-efl,mohamed--abdel-maksoud/chromium.src,littlstar/chromium.src,Jonekee/chromium.src,dushu1203/chromium.src,Chilledheart/chromium,bright-sparks/chromium-spacewalk,Just-D/chromium-1,hgl888/chromium-crosswalk,mohamed--abdel-maksoud/chromium.src,dushu1203/chromium.src,jaruba/chromium.src,axinging/chromium-crosswalk,crosswalk-project/chromium-crosswalk-efl,dednal/chromium.src,Fireblend/chromium-crosswalk,fujunwei/chromium-crosswalk,dushu1203/chromium.src,ondra-novak/chromium.src,dushu1203/chromium.src,PeterWangIntel/chromium-crosswalk,ltilve/chromium,jaruba/chromium.src,hgl888/chromium-crosswalk,crosswalk-project/chromium-crosswalk-efl,crosswalk-project/chromium-crosswalk-efl,jaruba/chromium.src,fujunwei/chromium-crosswalk,Pluto-tv/chromium-crosswalk,TheTypoMaster/chromium-crosswalk,jaruba/chromium.src,littlstar/chromium.src,markYoungH/chromium.src,ondra-novak/chromium.src,chuan9/chromium-crosswalk,jaruba/chromium.src,dushu1203/chromium.src,PeterWangIntel/chromium-crosswalk,jaruba/chromium.src,hgl888/chromium-crosswalk-efl,dushu1203/chromium.src,dushu1203/chromium.src,hgl888/chromium-crosswalk,dednal/chromium.src,crosswalk-project/chromium-crosswalk-efl,krieger-od/nwjs_chromium.src,bright-sparks/chromium-spacewalk,mohamed--abdel-maksoud/chromium.src,Jonekee/chromium.src,hgl888/chromium-crosswalk-efl,bright-sparks/chromium-spacewalk,hgl888/chromium-crosswalk-efl,ondra-novak/chromium.src,M4sse/chromium.src,axinging/chromium-crosswalk,ltilve/chromium,littlstar/chromium.src,krieger-od/nwjs_chromium.src,Fireblend/chromium-crosswalk,axinging/chromium-crosswalk,Jonekee/chromium.src,Chilledheart/chromium,dednal/chromium.src,axinging/chromium-crosswalk,krieger-od/nwjs_chromium.src,markYoungH/chromium.src,fujunwei/chromium-crosswalk,chuan9/chromium-crosswalk,Just-D/chromium-1,fujunwei/chromium-crosswalk,bright-sparks/chromium-spacewalk,hgl888/chromium-crosswalk-efl,M4sse/chromium.src,mohamed--abdel-maksoud/chromium.src,Jonekee/chromium.src,Chilledheart/chromium,chuan9/chromium-crosswalk,hgl888/chromium-crosswalk-efl,bright-sparks/chromium-spacewalk,Just-D/chromium-1,chuan9/chromium-crosswalk,krieger-od/nwjs_chromium.src,hgl888/chromium-crosswalk,Just-D/chromium-1,dushu1203/chromium.src,ondra-novak/chromium.src,littlstar/chromium.src,markYoungH/chromium.src,fujunwei/chromium-crosswalk,dednal/chromium.src,PeterWangIntel/chromium-crosswalk,Fireblend/chromium-crosswalk,ltilve/chromium,crosswalk-project/chromium-crosswalk-efl,ltilve/chromium,dednal/chromium.src,ondra-novak/chromium.src,axinging/chromium-crosswalk,dednal/chromium.src,fujunwei/chromium-crosswalk,Just-D/chromium-1,krieger-od/nwjs_chromium.src,Just-D/chromium-1,dednal/chromium.src,axinging/chromium-crosswalk,fujunwei/chromium-crosswalk,TheTypoMaster/chromium-crosswalk,dushu1203/chromium.src,ltilve/chromium,fujunwei/chromium-crosswalk,crosswalk-project/chromium-crosswalk-efl,axinging/chromium-crosswalk,markYoungH/chromium.src,Just-D/chromium-1,Pluto-tv/chromium-crosswalk,M4sse/chromium.src,M4sse/chromium.src,chuan9/chromium-crosswalk,TheTypoMaster/chromium-crosswalk,PeterWangIntel/chromium-crosswalk,M4sse/chromium.src,chuan9/chromium-crosswalk,hgl888/chromium-crosswalk,Chilledheart/chromium,ltilve/chromium,dushu1203/chromi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