[builtins] Introduce proper Float64Cos and Float64Sin.

src/base/ieee754.h

Index: src/base/ieee754.h
diff --git a/src/base/ieee754.h b/src/base/ieee754.h
index ffb20734c0f3dbcca72bb6c3c8d068eef3112842..3bb41514bac00dbea4c6d4256a947dda0db64ddd 100644
--- a/src/base/ieee754.h
+++ b/src/base/ieee754.h
@@ -17,6 +17,9 @@ double atan(double x);
 // the two arguments to determine the quadrant of the result.
 double atan2(double y, double x);
 
+// Returns the cosine of |x|, where |x| is given in radians.
+double cos(double x);
+
 // Returns the base-e exponential of |x|.
 double exp(double x);
 
@@ -29,18 +32,21 @@ double log(double x);
 // accurate even if the value of |x| is near zero.
 double log1p(double x);
 
-// Return the base 2 logarithm of |x|.
+// Returns the base 2 logarithm of |x|.
 double log2(double x);
 
-// Return the base 10 logarithm of |x|.
+// Returns the base 10 logarithm of |x|.
 double log10(double x);
 
-// Return cube root of |x|.
+// Returns the cube root of |x|.
 double cbrt(double x);
 
 // Returns exp(x)-1, the exponential of |x| minus 1.
 double expm1(double x);
 
+// Returns the sine of |x|, where |x| is given in radians.
+double sin(double x);
+
 }  // namespace ieee754
 }  // namespace base
 }  // namespace v8