Always use the caller's context in PepperTryCatchV8
Always use the caller's context in PepperTryCatchV8

This removes the DCHECK from PepperTryCatch which checks that the current
context is equal to the plugin context. This assumption is not always true.
In particular, if we call into the plugin directly from another frame (which
is in the same origin) the current context will differ. The same is true for background scripts. This should be ok; we should always use the calling context so as to not leak v8 objects across contexts.

BUG=412062

Review URL: https://codereview.chromium.org/555583003

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#294291}

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