Remove support for Object.observe

src/ic/x87/ic-x87.cc

Index: src/ic/x87/ic-x87.cc
diff --git a/src/ic/x87/ic-x87.cc b/src/ic/x87/ic-x87.cc
index 66e587383bc1cb0085388960869e8f8dfc8417ab..94919549c590adcea2dba705addfeca886199a10 100644
--- a/src/ic/x87/ic-x87.cc
+++ b/src/ic/x87/ic-x87.cc
@@ -519,10 +519,10 @@ void KeyedStoreIC::GenerateMegamorphic(MacroAssembler* masm,
   __ JumpIfSmi(receiver, &slow);
   // Get the map from the receiver.
   __ mov(edi, FieldOperand(receiver, HeapObject::kMapOffset));
-  // Check that the receiver does not require access checks and is not observed.
-  // The generic stub does not perform map checks or handle observed objects.
+  // Check that the receiver does not require access checks.
+  // The generic stub does not perform map checks.
   __ test_b(FieldOperand(edi, Map::kBitFieldOffset),
-            Immediate(1 << Map::kIsAccessCheckNeeded | 1 << Map::kIsObserved));
+            Immediate(1 << Map::kIsAccessCheckNeeded));
   __ j(not_zero, &slow);
   // Check that the key is a smi.
   __ JumpIfNotSmi(key, &maybe_name_key);