Implement cross-origin attributes using access check interceptors.

third_party/WebKit/Source/bindings/IDLExtendedAttributes.txt

Index: third_party/WebKit/Source/bindings/IDLExtendedAttributes.txt
diff --git a/third_party/WebKit/Source/bindings/IDLExtendedAttributes.txt b/third_party/WebKit/Source/bindings/IDLExtendedAttributes.txt
index 57f719302691eb175d1ea8f109d521eea691a73f..88621b958768017121df3da9017c3f855dd04feb 100644
--- a/third_party/WebKit/Source/bindings/IDLExtendedAttributes.txt
+++ b/third_party/WebKit/Source/bindings/IDLExtendedAttributes.txt
@@ -41,6 +41,7 @@ Constructor
 # FIXME: remove [ConstructorCallWith=Document], as can instead use
 # [ConstructorCallWith=ExecutionContext] + toDocument(executionContext)
 ConstructorCallWith=ExecutionContext|ScriptState|Document
+CrossOrigin=|Setter

[dcheng, 2016/10/24 07:56:38]

I'm uncertain about adding a new attribute. For now, it makes migrating code
from my handrolled manual bindings into the bindings generator easier. For the
final patchset to be reviewed, we definitely don't want both. We should either:
- Remove DoNotCheckSecurity
- Reuse it, but update the usage in the scripts as needed.

 Custom=|Getter|Setter|LegacyCallAsFunction|VisitDOMWrapper|PropertyGetter|PropertyEnumerator|PropertyQuery|CallPrologue|CallEpilogue
 CustomConstructor
 CustomElementCallbacks