cleanup patch generation to preseve comments and remove @patch

test/dart_codegen/expect/core/double.dart

 part of dart.core;
 
 abstract class double extends num {
   static const double NAN = 0.0 / 0.0;
   static const double INFINITY = 1.0 / 0.0;
   static const double NEGATIVE_INFINITY = -INFINITY;
   static const double MIN_POSITIVE = 5e-324;
   static const double MAX_FINITE = 1.7976931348623157e+308;
   double remainder(num other);
   double operator +(num other);
   double operator -(num other);
   double operator *(num other);
   double operator %(num other);
   double operator /(num other);
   int operator ~/(num other);
   double operator -();
   double abs();
   double get sign;
   int round();
   int floor();
   int ceil();
   int truncate();
   double roundToDouble();
   double floorToDouble();
   double ceilToDouble();
   double truncateToDouble();
   String toString();
-  @patch static double parse(String source, [double onError(String source)]) {
+  static double parse(String source, [double onError(String source)]) {
     return ((__x10) => DDC$RT.cast(__x10, dynamic, double, "CastGeneral",
-        """line 173, column 12 of dart:core/double.dart: """, __x10 is double,
+        """line 206, column 12 of dart:core/double.dart: """, __x10 is double,
         true))(Primitives.parseDouble(source, onError));
   }
 }