fetch: Add [NewObject] to IDL declarations that have it in the spec.

Several IDL methods have been annotated with the [NewObject] extended
attribute since 2014 (Fetch spec commit 92f9337cd2, "Sprinkle [NewObject],
[SameObject] love").

Add it to our IDLs for spec compliance. In practice, at the moment this is a
no-op for methods that return promises and it adds a DCHECK for methods that
return interface types.

Request.clone() and Response.clone() also need the Blink-specific
[DoNotTestNewObject] extended attribute, as their C++ implementations call
ToV8() on the new object they return, which causes the DCHECKs to fail (in
other words, [NewObject] becomes a no-op for them as well).

Bug: 769221

Change-Id: If1d598660efef656d165a79618a45ea8ddc99e30
Reviewed-on: https://chromium-review.googlesource.com/685658Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: Raphael Kubo da Costa (rakuco) <raphael.kubo.da.costa@intel.com>
Cr-Commit-Position: refs/heads/master@{#504717}

third_party/WebKit/Source/modules/fetch/Body.idl

@@ -11,11 +11,11 @@
     NoInterfaceObject
 ] interface Body {
     readonly attribute boolean bodyUsed;
-    [CallWith=ScriptState] Promise<ArrayBuffer> arrayBuffer();
-    [CallWith=ScriptState] Promise<Blob> blob();
-    [CallWith=ScriptState] Promise<FormData> formData();
-    [CallWith=ScriptState] Promise<JSON> json();
-    [CallWith=ScriptState] Promise<USVString> text();
+    [CallWith=ScriptState, NewObject] Promise<ArrayBuffer> arrayBuffer();
+    [CallWith=ScriptState, NewObject] Promise<Blob> blob();
+    [CallWith=ScriptState, NewObject] Promise<FormData> formData();
+    [CallWith=ScriptState, NewObject] Promise<JSON> json();
+    [CallWith=ScriptState, NewObject] Promise<USVString> text();
 
     // body attribute is defined in sub-interfaces, because the IDL processor
     // cannot deal with attribute inheritance with runtime enabled flag.

third_party/WebKit/Source/modules/fetch/Request.idl

@@ -42,7 +42,7 @@ enum ReferrerPolicy {
     readonly attribute RequestRedirect redirect;
     readonly attribute DOMString integrity;
 
-    [RaisesException, CallWith=ScriptState] Request clone();
+    [RaisesException, CallWith=ScriptState, DoNotTestNewObject, NewObject] Request clone();
 };
 
 Request implements Body;

third_party/WebKit/Source/modules/fetch/Response.idl

@@ -16,8 +16,8 @@ enum ResponseType { "basic", "cors", "default", "error", "opaque", "opaqueredire
     Exposed=(Window,Worker),
     RaisesException=Constructor
 ] interface Response {
-    [CallWith=ScriptState] static Response error();
-    [CallWith=ScriptState, RaisesException] static Response redirect(USVString url, optional unsigned short status = 302);
+    [CallWith=ScriptState, NewObject] static Response error();
+    [CallWith=ScriptState, NewObject, RaisesException] static Response redirect(USVString url, optional unsigned short status = 302);
     readonly attribute ResponseType type;
     readonly attribute USVString url;
     readonly attribute boolean redirected;
@@ -26,7 +26,7 @@ enum ResponseType { "basic", "cors", "default", "error", "opaque", "opaqueredire
     readonly attribute ByteString statusText;
     readonly attribute Headers headers;
 
-    [RaisesException, CallWith=ScriptState] Response clone();
+    [RaisesException, CallWith=ScriptState, DoNotTestNewObject, NewObject] Response clone();
 
     [CallWith=ScriptState, MeasureAs=FetchBodyStream] readonly attribute any body;
 };

third_party/WebKit/Source/modules/fetch/WindowFetch.idl

@@ -5,5 +5,5 @@
 [
     ImplementedAs=GlobalFetch
 ] partial interface Window {
-    [CallWith=ScriptState, RaisesException] Promise<Response> fetch(RequestInfo input, optional Dictionary init);
+    [CallWith=ScriptState, NewObject, RaisesException] Promise<Response> fetch(RequestInfo input, optional Dictionary init);
 };

third_party/WebKit/Source/modules/fetch/WorkerFetch.idl

@@ -5,5 +5,5 @@
 [
     ImplementedAs=GlobalFetch
 ] partial interface WorkerGlobalScope {
-    [CallWith=ScriptState, RaisesException] Promise<Response> fetch(RequestInfo input, optional Dictionary init);
+    [CallWith=ScriptState, NewObject, RaisesException] Promise<Response> fetch(RequestInfo input, optional Dictionary init);
 };