fix benchmarks

R=arv
BUG=

Review URL: https://codereview.appspot.com/76130043

benchmark/d8_benchmarks.js

@@ -12,13 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-/*
-  This is a harness so that the ChangeSummary benchmarks can be run and profiled
-  using V8's d8 shell. Doing requires modifying V8's src/object-observe.js to
-  expose full delivery of all pending changes to observers via
-  Object.deliverAllChangesRecords(). This is *not* a part of the spec and is
-  just a hack to allow profiling the benchmarks from d8.
-*/
+// Flags: --allow-natives-syntax
 
 var console = {
   log: print

src/observe.js

@@ -621,7 +621,14 @@
 
   var runningMicrotaskCheckpoint = false;
 
-  var hasDebugForceFullDelivery = typeof Object.deliverAllChangeRecords == 'function';
+  var hasDebugForceFullDelivery = hasObserve && (function() {
+    try {
+      eval('%RunMicrotasks()');
+      return true;
+    } catch (ex) {
+      return false;
+    }
+  })();
 
   global.Platform = global.Platform || {};
 
@@ -630,7 +637,7 @@
       return;
 
     if (hasDebugForceFullDelivery) {
-      Object.deliverAllChangeRecords();
+      eval('%RunMicrotasks()');
       return;
     }