Porting Math.pow changes to x64.

src/x64/assembler-x64.cc

Index: src/x64/assembler-x64.cc
diff --git a/src/x64/assembler-x64.cc b/src/x64/assembler-x64.cc
index f07a0ddee592faeb6cb7f117a8642a7516036e3a..ca3bece5f09d2146884a276471a54e8d5fb8c6e7 100644
--- a/src/x64/assembler-x64.cc
+++ b/src/x64/assembler-x64.cc
@@ -2307,6 +2307,27 @@ void Assembler::fyl2x() {
 }
 
 
+void Assembler::f2xm1() {
+  EnsureSpace ensure_space(this);
+  emit(0xD9);
+  emit(0xF0);
+}
+
+
+void Assembler::fscale() {
+  EnsureSpace ensure_space(this);
+  emit(0xD9);
+  emit(0xFD);
+}
+
+
+void Assembler::fninit() {
+  EnsureSpace ensure_space(this);
+  emit(0xDB);
+  emit(0xE3);
+}
+
+
 void Assembler::fadd(int i) {
   EnsureSpace ensure_space(this);
   emit_farith(0xDC, 0xC0, i);