Use dart.tearoff helper at tearoff sites

lib/runtime/dart/_js_helper.js

Index: lib/runtime/dart/_js_helper.js
diff --git a/lib/runtime/dart/_js_helper.js b/lib/runtime/dart/_js_helper.js
index 5f563a6433e5f4e6b4e9b5baf2da13b98d301f6f..cb5a6c080cb2bd65388f54bd2f5b9c7fbce84f2c 100644
--- a/lib/runtime/dart/_js_helper.js
+++ b/lib/runtime/dart/_js_helper.js
@@ -2844,7 +2844,7 @@ var _isolate_helper = dart.lazyImport(_isolate_helper);
           };
         }(functionType);
       } else if (!dart.notNull(isStatic) && typeof functionType == "function") {
-        let getReceiver = isIntercepted ? _foreign_helper.RAW_DART_FUNCTION_REF(dart.bind(BoundClosure, 'receiverOf')) : _foreign_helper.RAW_DART_FUNCTION_REF(dart.bind(BoundClosure, 'selfOf'));
+        let getReceiver = isIntercepted ? _foreign_helper.RAW_DART_FUNCTION_REF(BoundClosure.receiverOf) : _foreign_helper.RAW_DART_FUNCTION_REF(BoundClosure.selfOf);
         signatureFunction = function(f, r) {
           return function() {
             return f.apply({$receiver: r(this)}, arguments$);
@@ -2866,7 +2866,7 @@ var _isolate_helper = dart.lazyImport(_isolate_helper);
       return constructor;
     }
     static cspForwardCall(arity, isSuperCall, stubName, func) {
-      let getSelf = _foreign_helper.RAW_DART_FUNCTION_REF(dart.bind(BoundClosure, 'selfOf'));
+      let getSelf = _foreign_helper.RAW_DART_FUNCTION_REF(BoundClosure.selfOf);
       if (isSuperCall)
         arity = -1;
       switch (arity) {
@@ -2957,8 +2957,8 @@ var _isolate_helper = dart.lazyImport(_isolate_helper);
       })()}` + '}')();
     }
     static cspForwardInterceptedCall(arity, isSuperCall, name, func) {
-      let getSelf = _foreign_helper.RAW_DART_FUNCTION_REF(dart.bind(BoundClosure, 'selfOf'));
-      let getReceiver = _foreign_helper.RAW_DART_FUNCTION_REF(dart.bind(BoundClosure, 'receiverOf'));
+      let getSelf = _foreign_helper.RAW_DART_FUNCTION_REF(BoundClosure.selfOf);
+      let getReceiver = _foreign_helper.RAW_DART_FUNCTION_REF(BoundClosure.receiverOf);
       if (isSuperCall)
         arity = -1;
       switch (arity) {