Introduce a base pointer field in FixedTypedArrayBase and teach GC about it

src/hydrogen-instructions.h

 // Copyright 2012 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.
 
 #ifndef V8_HYDROGEN_INSTRUCTIONS_H_
 #define V8_HYDROGEN_INSTRUCTIONS_H_
 
 #include <cstring>
 #include <iosfwd>
 
@@ skipping 5910 matching lines @@
                          Handle<String>::null(), false, false);
   }
 
   static HObjectAccess ForFixedArrayLength() {
     return HObjectAccess(
         kArrayLengths,
         FixedArray::kLengthOffset,
         Representation::Smi());
   }
 
+  static HObjectAccess ForFixedTypedArrayBaseBasePointer() {
+    return HObjectAccess(kInobject, FixedTypedArrayBase::kBasePointerOffset,
+                         Representation::Tagged());
+  }
+
   static HObjectAccess ForStringHashField() {
     return HObjectAccess(kInobject,
                          String::kHashFieldOffset,
                          Representation::Integer32());
   }
 
   static HObjectAccess ForStringLength() {
     STATIC_ASSERT(String::kMaxLength <= Smi::kMaxValue);
     return HObjectAccess(
         kStringLengths,
@@ skipping 1951 matching lines @@
 };
 
 
 
 #undef DECLARE_INSTRUCTION
 #undef DECLARE_CONCRETE_INSTRUCTION
 
 } }  // namespace v8::internal
 
 #endif  // V8_HYDROGEN_INSTRUCTIONS_H_