Remove support for Object.observe

src/ic/arm/ic-arm.cc

Index: src/ic/arm/ic-arm.cc
diff --git a/src/ic/arm/ic-arm.cc b/src/ic/arm/ic-arm.cc
index 59eae6d98b135def2a6c21b9584f4de56ea73482..b0bcc886acd540ffc78a8b6ac06f29def913679e 100644
--- a/src/ic/arm/ic-arm.cc
+++ b/src/ic/arm/ic-arm.cc
@@ -626,10 +626,10 @@ void KeyedStoreIC::GenerateMegamorphic(MacroAssembler* masm,
   __ JumpIfSmi(receiver, &slow);
   // Get the map of the object.
   __ ldr(receiver_map, FieldMemOperand(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.
   __ ldrb(ip, FieldMemOperand(receiver_map, Map::kBitFieldOffset));
-  __ tst(ip, Operand(1 << Map::kIsAccessCheckNeeded | 1 << Map::kIsObserved));
+  __ tst(ip, Operand(1 << Map::kIsAccessCheckNeeded));
   __ b(ne, &slow);
   // Check if the object is a JS array or not.
   __ ldrb(r4, FieldMemOperand(receiver_map, Map::kInstanceTypeOffset));