Remove support for Object.observe

src/ic/arm64/ic-arm64.cc

Index: src/ic/arm64/ic-arm64.cc
diff --git a/src/ic/arm64/ic-arm64.cc b/src/ic/arm64/ic-arm64.cc
index e68e40186a3173fdf918c9edf6dd80b704849378..3fd384ecdbb6f7e7552602a1229283a18bee44ea 100644
--- a/src/ic/arm64/ic-arm64.cc
+++ b/src/ic/arm64/ic-arm64.cc
@@ -622,11 +622,10 @@ void KeyedStoreIC::GenerateMegamorphic(MacroAssembler* masm,
   __ JumpIfSmi(receiver, &slow);
   __ 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(x10, FieldMemOperand(receiver_map, Map::kBitFieldOffset));
-  __ TestAndBranchIfAnySet(
-      x10, (1 << Map::kIsAccessCheckNeeded) | (1 << Map::kIsObserved), &slow);
+  __ TestAndBranchIfAnySet(x10, (1 << Map::kIsAccessCheckNeeded), &slow);
 
   // Check if the object is a JS array or not.
   Register instance_type = x10;