Remove support for Object.observe

src/ic/s390/ic-s390.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #if V8_TARGET_ARCH_S390
 
 #include "src/ic/ic.h"
 #include "src/codegen.h"
 #include "src/ic/ic-compiler.h"
 #include "src/ic/stub-cache.h"
@@ skipping 607 matching lines @@
   Register elements_map = r8;
   Register elements = r9;  // Elements array of the receiver.
   // r6 and r7 are used as general scratch registers.
 
   // Check that the key is a smi.
   __ JumpIfNotSmi(key, &maybe_name_key);
   // Check that the object isn't a smi.
   __ JumpIfSmi(receiver, &slow);
   // Get the map of the object.
   __ LoadP(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.
   __ LoadlB(ip, FieldMemOperand(receiver_map, Map::kBitFieldOffset));
-  __ AndP(r0, ip,
-          Operand(1 << Map::kIsAccessCheckNeeded | 1 << Map::kIsObserved));
+  __ AndP(r0, ip, Operand(1 << Map::kIsAccessCheckNeeded));
   __ bne(&slow, Label::kNear);
   // Check if the object is a JS array or not.
   __ LoadlB(r6, FieldMemOperand(receiver_map, Map::kInstanceTypeOffset));
   __ CmpP(r6, Operand(JS_ARRAY_TYPE));
   __ beq(&array);
   // Check that the object is some kind of JSObject.
   __ CmpP(r6, Operand(FIRST_JS_OBJECT_TYPE));
   __ blt(&slow, Label::kNear);
 
   // Object case: Check key against length in the elements array.
@@ skipping 245 matching lines @@
     patcher.masm()->brcl(cc, Operand((branch_instr & 0xffffffff) << 1));
   } else {
     DCHECK(false);
   }
 }
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_S390