Implement Math.pow using FPU instructions and inline it in crankshaft (ia32).

src/assembler.cc

Index: src/assembler.cc
diff --git a/src/assembler.cc b/src/assembler.cc
index bc05c01800dc51889ee58e31264d533045be84ff..e1cf13ff71a6a53604c0137d50784859f12e1c30 100644
--- a/src/assembler.cc
+++ b/src/assembler.cc
@@ -1113,6 +1113,9 @@ double power_double_int(double x, int y) {
 
 
 double power_double_double(double x, double y) {
+  // The checks for special cases can be dropped in ia32 because it has already
+  // been done in generated code before bailing out here.
+#if !defined(V8_TARGET_ARCH_IA32)
   int y_int = static_cast<int>(y);
   if (y == y_int) {
     return power_double_int(x, y_int);  // Returns 1.0 for exponent 0.
@@ -1121,6 +1124,7 @@ double power_double_double(double x, double y) {
     if (y == 0.5) return sqrt(x + 0.0);  // -0 must be converted to +0.
     if (y == -0.5) return 1.0 / sqrt(x + 0.0);
   }
+#endif
   if (isnan(y) || ((x == 1 || x == -1) && isinf(y))) {
     return OS::nan_value();
   }