Stack trace API: poison stack frames below the first strict mode frame.

src/isolate.cc

Index: src/isolate.cc
diff --git a/src/isolate.cc b/src/isolate.cc
index 632ecdc50a32b569ba3224c9428a165ef10deccb..15a99dd2bf5f55569a0b9ab196bb4039ff43d009 100644
--- a/src/isolate.cc
+++ b/src/isolate.cc
@@ -617,8 +617,11 @@ Handle<JSArray> Isolate::CaptureSimpleStackTrace(Handle<JSObject> error_object,
   // If the caller parameter is a function we skip frames until we're
   // under it before starting to collect.
   bool seen_caller = !caller->IsJSFunction();
-  int cursor = 0;
+  // First element is reserved to store the number of non-strict frames.
+  int cursor = 1;
   int frames_seen = 0;
+  int non_strict_frames = 0;
+  bool encountered_strict_function = false;
   for (StackFrameIterator iter(this);
        !iter.done() && frames_seen < limit;
        iter.Advance()) {
@@ -646,6 +649,17 @@ Handle<JSArray> Isolate::CaptureSimpleStackTrace(Handle<JSObject> error_object,
         Handle<JSFunction> fun = frames[i].function();
         Handle<Code> code = frames[i].code();
         Handle<Smi> offset(Smi::FromInt(frames[i].offset()), this);
+        // The stack trace API should not expose receivers and function
+        // objects on frames deeper than the top-most one with a strict
+        // mode function.  The number of non-strict frames is stored as
+        // first element in the result array.
+        if (!encountered_strict_function) {
+          if (!fun->shared()->is_classic_mode()) {
+            encountered_strict_function = true;
+          } else {
+            non_strict_frames++;
+          }
+        }
         elements->set(cursor++, *recv);
         elements->set(cursor++, *fun);
         elements->set(cursor++, *code);
@@ -653,6 +667,7 @@ Handle<JSArray> Isolate::CaptureSimpleStackTrace(Handle<JSObject> error_object,
       }
     }
   }
+  elements->set(0, Smi::FromInt(non_strict_frames));
   Handle<JSArray> result = factory()->NewJSArrayWithElements(elements);
   result->set_length(Smi::FromInt(cursor));
   return result;