ScriptState is an abstraction of JavaScript VM execution state that works for both V8 and JSC. When possible WebCore code should manipulate this abstraction instead of using v8::Context directly. The ScriptState instance can be retrieved from ScriptController(for main isolated world) or from V8IsolatedWorld.
Note that V8IsolatedWorld is going to lose its ScriptState soon to more closely match how JSC does things.
Closing some V8-related work items.