Update documentation on trignometric functions.

sdk/lib/_internal/js_runtime/lib/math_patch.dart

Index: sdk/lib/_internal/js_runtime/lib/math_patch.dart
diff --git a/sdk/lib/_internal/js_runtime/lib/math_patch.dart b/sdk/lib/_internal/js_runtime/lib/math_patch.dart
index 0179c4f68f444a26d15ce674aad5c9beaa0c3b6a..5148540229c88ee7d1838ba9ecdb5f0b6b04f7c5 100644
--- a/sdk/lib/_internal/js_runtime/lib/math_patch.dart
+++ b/sdk/lib/_internal/js_runtime/lib/math_patch.dart
@@ -11,13 +11,13 @@ import 'dart:typed_data' show ByteData;
 double sqrt(num x) => JS('num', r'Math.sqrt(#)', checkNum(x));
 
 @patch
-double sin(num x) => JS('num', r'Math.sin(#)', checkNum(x));
+double sin(num radians) => JS('num', r'Math.sin(#)', checkNum(radians));
 
 @patch
-double cos(num x) => JS('num', r'Math.cos(#)', checkNum(x));
+double cos(num radians) => JS('num', r'Math.cos(#)', checkNum(radians));
 
 @patch
-double tan(num x) => JS('num', r'Math.tan(#)', checkNum(x));
+double tan(num radians) => JS('num', r'Math.tan(#)', checkNum(radians));
 
 @patch
 double acos(num x) => JS('num', r'Math.acos(#)', checkNum(x));