Model each Dart library as its own ScriptState when devtools are enabled.

Source/bindings/v8/custom/V8InjectedScriptManager.cpp

Index: Source/bindings/v8/custom/V8InjectedScriptManager.cpp
diff --git a/Source/bindings/v8/custom/V8InjectedScriptManager.cpp b/Source/bindings/v8/custom/V8InjectedScriptManager.cpp
index 199b84cd120eeefbb4dd63614032b5c7dce8a3f0..cc880e48eba6def5ea85cea92be19e8d223002b8 100644
--- a/Source/bindings/v8/custom/V8InjectedScriptManager.cpp
+++ b/Source/bindings/v8/custom/V8InjectedScriptManager.cpp
@@ -37,6 +37,7 @@
 #include "bindings/v8/ScriptDebugServer.h"
 #include "bindings/v8/ScriptObject.h"
 #include "bindings/v8/V8Binding.h"
+#include "bindings/v8/V8HiddenPropertyName.h"
 #include "bindings/v8/V8ObjectConstructor.h"
 #include "bindings/v8/V8ScriptRunner.h"
 #include "core/inspector/InjectedScriptHost.h"
@@ -82,6 +83,13 @@ ScriptObject InjectedScriptManager::createInjectedScript(const String& scriptSou
     if (scriptHostWrapper.IsEmpty())
         return ScriptObject();
 
+    // Store the inspectedScriptState on the scriptHostWrapper if it is
+    // different from the ScriptState associated with the context.
+    // This is needed to support Dart as Dart does not create a separate V8
+    // context for every Dart library.
+    if (inspectedScriptState != ScriptState::forContext(inspectedContext))
+        scriptHostWrapper->SetHiddenValue(V8HiddenPropertyName::scriptState(), v8::External::New(inspectedScriptState));
+
     // Inject javascript into the context. The compiled script is supposed to evaluate into
     // a single anonymous function(it's anonymous to avoid cluttering the global object with
     // inspector's stuff) the function is called a few lines below with InjectedScriptHost wrapper,
@@ -94,6 +102,7 @@ ScriptObject InjectedScriptManager::createInjectedScript(const String& scriptSou
     v8::Local<v8::Object> windowGlobal = inspectedContext->Global();
     v8::Handle<v8::Value> args[] = { scriptHostWrapper, windowGlobal, v8::Number::New(id) };
     v8::Local<v8::Value> injectedScriptValue = V8ScriptRunner::callInternalFunction(v8::Local<v8::Function>::Cast(value), windowGlobal, WTF_ARRAY_LENGTH(args), args, inspectedContext->GetIsolate());
+
     return ScriptObject(inspectedScriptState, v8::Handle<v8::Object>::Cast(injectedScriptValue));
 }