Add "has fast elements" bit to maps and use it in inlined keyed loads.

src/arm/assembler-arm.h

 // Copyright (c) 1994-2006 Sun Microsystems Inc.
 // 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.
 //
@@ skipping 1092 matching lines @@
   void BlockConstPoolBefore(int pc_offset) {
     if (no_const_pool_before_ < pc_offset) no_const_pool_before_ = pc_offset;
   }
 
   void StartBlockConstPool() {
     const_pool_blocked_nesting_++;
   }
   void EndBlockConstPool() {
     const_pool_blocked_nesting_--;
   }
+  bool is_const_pool_blocked() const { return const_pool_blocked_nesting_ > 0; }
 
  private:
   // Code buffer:
   // The buffer into which code and relocation info are generated.
   byte* buffer_;
   int buffer_size_;
   // True if the assembler owns the buffer, false if buffer is external.
   bool own_buffer_;
 
   // Buffer size and constant pool distance are checked together at regular
@@ skipping 90 matching lines @@
 
   friend class RegExpMacroAssemblerARM;
   friend class RelocInfo;
   friend class CodePatcher;
   friend class BlockConstPoolScope;
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_ARM_ASSEMBLER_ARM_H_