Implement API for accessing fonts installed locally on the system.

third_party/WebKit/Source/core/css/FontFaceSet.idl

Index: third_party/WebKit/Source/core/css/FontFaceSet.idl
diff --git a/third_party/WebKit/Source/core/css/FontFaceSet.idl b/third_party/WebKit/Source/core/css/FontFaceSet.idl
index ce3eb1d34dd8038e33f308f9cb6bcb1a5980b889..0133694adcd197d6971c17a6d4ff5345d14b7694 100644
--- a/third_party/WebKit/Source/core/css/FontFaceSet.idl
+++ b/third_party/WebKit/Source/core/css/FontFaceSet.idl
@@ -37,7 +37,7 @@ enum FontFaceSetLoadStatus { "loading", "loaded" };
 [
     ActiveDOMObject,
     SetWrapperReferenceFrom=document,
-    NoInterfaceObject,
+    Exposed=(Window),
 ] interface FontFaceSet : EventTarget {
     setlike<FontFace>;
     readonly attribute unsigned long size;
@@ -60,4 +60,6 @@ enum FontFaceSetLoadStatus { "loading", "loaded" };
 
     // loading state, "loading" while one or more fonts loading, "loaded" otherwise
     readonly attribute FontFaceSetLoadStatus status;
+
+    [CallWith=ScriptState, RuntimeEnabled=FontAccess, APIExperimentEnabled=FontAccess] static readonly attribute Promise systemFonts;
 };