Allow the optimizing code generator to call Math.pow with untagged doubles.

src/assembler.h

Index: src/assembler.h
===================================================================
--- src/assembler.h	(revision 5948)
+++ src/assembler.h	(working copy)
@@ -50,6 +50,7 @@
  public:
   static const double min_int;
   static const double one_half;
+  static const double negative_infinity;
 };
 
 
@@ -539,6 +540,8 @@
 
   static ExternalReference double_fp_operation(Token::Value operation);
   static ExternalReference compare_doubles();
+  static ExternalReference power_double_double_function();
+  static ExternalReference power_double_int_function();
 
   static ExternalReference handle_scope_next_address();
   static ExternalReference handle_scope_limit_address();
@@ -549,6 +552,7 @@
   // Static variables containing common double constants.
   static ExternalReference address_of_min_int();
   static ExternalReference address_of_one_half();
+  static ExternalReference address_of_negative_infinity();
 
   Address address() const {return reinterpret_cast<Address>(address_);}
 
@@ -710,6 +714,10 @@
   return num_bits_set;
 }
 
+// Computes pow(x, y) with the special cases in the spec for Math.pow.
+double power_double_int(double x, int y);
+double power_double_double(double x, double y);
+
 } }  // namespace v8::internal
 
 #endif  // V8_ASSEMBLER_H_