[heap] Remove unused code for TypedArrays in RightTrim.

This code is never used, and we don't right trim TypedArrays.

Bug: 
Change-Id: Ic3e32b194fb10ecd067449c755b1982c87c98257
Reviewed-on: https://chromium-review.googlesource.com/721541Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Peter Marshall <petermarshall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48623}

src/heap/heap.cc

@@ -2903,12 +2903,8 @@ void Heap::RightTrimFixedArray(FixedArrayBase* object, int elements_to_trim) {
   DCHECK_GE(elements_to_trim, 0);
 
   int bytes_to_trim;
-  if (object->IsFixedTypedArrayBase()) {
-    InstanceType type = object->map()->instance_type();
-    bytes_to_trim =
-        FixedTypedArrayBase::TypedArraySize(type, len) -
-        FixedTypedArrayBase::TypedArraySize(type, len - elements_to_trim);
-  } else if (object->IsByteArray()) {
+  DCHECK(!object->IsFixedTypedArrayBase());
+  if (object->IsByteArray()) {
     int new_size = ByteArray::SizeFor(len - elements_to_trim);
     bytes_to_trim = ByteArray::SizeFor(len) - new_size;
     DCHECK_GE(bytes_to_trim, 0);

test/cctest/heap/test-heap.cc

@@ -4742,58 +4742,6 @@ TEST(WritableVsImmortalRoots) {
   }
 }
 
-
-static void TestRightTrimFixedTypedArray(i::ExternalArrayType type,
-                                         int initial_length,
-                                         int elements_to_trim) {
-  v8::HandleScope scope(CcTest::isolate());
-  Isolate* isolate = CcTest::i_isolate();
-  Factory* factory = isolate->factory();
-  Heap* heap = isolate->heap();
-
-  Handle<FixedTypedArrayBase> array =
-      factory->NewFixedTypedArray(initial_length, type, true);
-  int old_size = array->size();
-  heap->RightTrimFixedArray(*array, elements_to_trim);
-
-  // Check that free space filler is at the right place and did not smash the
-  // array header.
-  CHECK(array->IsFixedArrayBase());
-  CHECK_EQ(initial_length - elements_to_trim, array->length());
-  int new_size = array->size();
-  if (new_size != old_size) {
-    // Free space filler should be created in this case.
-    Address next_obj_address = array->address() + array->size();
-    CHECK(HeapObject::FromAddress(next_obj_address)->IsFiller());
-  }
-  CcTest::CollectAllAvailableGarbage();
-}
-
-
-TEST(Regress472513) {
-  CcTest::InitializeVM();
-  v8::HandleScope scope(CcTest::isolate());
-
-  // The combination of type/initial_length/elements_to_trim triggered
-  // typed array header smashing with free space filler (crbug/472513).
-
-  // 64-bit cases.
-  TestRightTrimFixedTypedArray(i::kExternalUint8Array, 32, 6);
-  TestRightTrimFixedTypedArray(i::kExternalUint8Array, 32 - 7, 6);
-  TestRightTrimFixedTypedArray(i::kExternalUint16Array, 16, 6);
-  TestRightTrimFixedTypedArray(i::kExternalUint16Array, 16 - 3, 6);
-  TestRightTrimFixedTypedArray(i::kExternalUint32Array, 8, 6);
-  TestRightTrimFixedTypedArray(i::kExternalUint32Array, 8 - 1, 6);
-
-  // 32-bit cases.
-  TestRightTrimFixedTypedArray(i::kExternalUint8Array, 16, 3);
-  TestRightTrimFixedTypedArray(i::kExternalUint8Array, 16 - 3, 3);
-  TestRightTrimFixedTypedArray(i::kExternalUint16Array, 8, 3);
-  TestRightTrimFixedTypedArray(i::kExternalUint16Array, 8 - 1, 3);
-  TestRightTrimFixedTypedArray(i::kExternalUint32Array, 4, 3);
-}
-
-
 TEST(WeakFixedArray) {
   CcTest::InitializeVM();
   v8::HandleScope scope(CcTest::isolate());