Add kHeaderSize constant to SeqString.

src/arm/code-stubs-arm.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 4557 matching lines @@
   __ add(r0, r0, Operand(r2));
   __ str(r0, MemOperand(sp, 2 * kPointerSize));
 
   // Argument 5 (sp[4]): static offsets vector buffer.
   __ mov(r0,
          Operand(ExternalReference::address_of_static_offsets_vector(isolate)));
   __ str(r0, MemOperand(sp, 1 * kPointerSize));
 
   // For arguments 4 and 3 get string length, calculate start of string data and
   // calculate the shift of the index (0 for ASCII and 1 for two byte).
-  STATIC_ASSERT(SeqAsciiString::kHeaderSize == SeqTwoByteString::kHeaderSize);
-  __ add(r8, subject, Operand(SeqAsciiString::kHeaderSize - kHeapObjectTag));
+  __ add(r8, subject, Operand(SeqString::kHeaderSize - kHeapObjectTag));
   __ eor(r3, r3, Operand(1));
   // Load the length from the original subject string from the previous stack
   // frame. Therefore we have to use fp, which points exactly to two pointer
   // sizes below the previous sp. (Because creating a new stack frame pushes
   // the previous fp onto the stack and moves up sp by 2 * kPointerSize.)
   __ ldr(subject, MemOperand(fp, kSubjectOffset + 2 * kPointerSize));
   // If slice offset is not 0, load the length from the original sliced string.
   // Argument 4, r3: End of string data
   // Argument 3, r2: Start of string data
   // Prepare start and end index of the input.
@@ skipping 2475 matching lines @@
 
   // Fall through when we need to inform the incremental marker.
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM