Implement Math.tan in generated code.

src/assembler.cc

Index: src/assembler.cc
diff --git a/src/assembler.cc b/src/assembler.cc
index 4dc2394b06076916baa012c4a77223d11e867e3b..bc05c01800dc51889ee58e31264d533045be84ff 100644
--- a/src/assembler.cc
+++ b/src/assembler.cc
@@ -1051,6 +1051,11 @@ static double math_cos_double(double x) {
 }
 
 
+static double math_tan_double(double x) {
+  return tan(x);
+}
+
+
 static double math_log_double(double x) {
   return log(x);
 }
@@ -1072,6 +1077,14 @@ ExternalReference ExternalReference::math_cos_double_function(
 }
 
 
+ExternalReference ExternalReference::math_tan_double_function(
+    Isolate* isolate) {
+  return ExternalReference(Redirect(isolate,
+                                    FUNCTION_ADDR(math_tan_double),
+                                    BUILTIN_FP_CALL));
+}
+
+
 ExternalReference ExternalReference::math_log_double_function(
     Isolate* isolate) {
   return ExternalReference(Redirect(isolate,