Remove dart backend

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();
- external static double parse(String source, [double onError(String source)]);
-}