[Fetch API] Implement Request.formData and Response.formData.

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

Index: third_party/WebKit/Source/modules/fetch/Body.idl
diff --git a/third_party/WebKit/Source/modules/fetch/Body.idl b/third_party/WebKit/Source/modules/fetch/Body.idl
index c00f5c568dc0f3b3c72bdfbad5226180f37b72a5..a9312bc215892f79430fd407622781dffa5ab99c 100644
--- a/third_party/WebKit/Source/modules/fetch/Body.idl
+++ b/third_party/WebKit/Source/modules/fetch/Body.idl
@@ -13,13 +13,11 @@
     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();
 
     // body attribute is defined in sub-interfaces, because the IDL processor
     // cannot deal with attribute inheritance with runtime enabled flag.
     // [RuntimeEnabled=ExperimentalStream] readonly attribute ReadableByteStream body;
-
-    // Still to be implemented.
-    // [CallWith=ScriptState] Promise<FormData> formData();
 };