Lazily initialize fast_sqrt() and pass an Isolate parameter to it

src/assembler.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 1119 matching lines @@
   unsigned int num_bits_set;
   for (num_bits_set = 0; x; x >>= 1) {
     num_bits_set += x & 1;
   }
   return num_bits_set;
 }
 
 bool EvalComparison(Token::Value op, double op1, double op2);
 
 // Computes pow(x, y) with the special cases in the spec for Math.pow.
-double power_helper(double x, double y);
+double power_helper(Isolate* isolate, double x, double y);
 double power_double_int(double x, int y);
 double power_double_double(double x, double y);
 
 // Helper class for generating code or data associated with the code
 // right after a call instruction. As an example this can be used to
 // generate safepoint data after calls for crankshaft.
 class CallWrapper {
  public:
   CallWrapper() { }
   virtual ~CallWrapper() { }
@@ skipping 128 matching lines @@
     std::vector<ConstantPoolEntry> shared_entries;
   };
 
   Label emitted_label_;  // Records pc_offset of emitted pool
   PerTypeEntryInfo info_[ConstantPoolEntry::NUMBER_OF_TYPES];
 };
 
 }  // namespace internal
 }  // namespace v8
 #endif  // V8_ASSEMBLER_H_