Remove support for operator negate and replace occurrences with unary

lib/compiler/implementation/lib/interceptors.dart

Index: lib/compiler/implementation/lib/interceptors.dart
diff --git a/lib/compiler/implementation/lib/interceptors.dart b/lib/compiler/implementation/lib/interceptors.dart
index 4e936501974b14b61e19221644e0f9a61ebc8693..8ca99f3a3151afe080eb7ec529b72c4cebdb34b0 100644
--- a/lib/compiler/implementation/lib/interceptors.dart
+++ b/lib/compiler/implementation/lib/interceptors.dart
@@ -414,13 +414,6 @@ isInfinite(receiver) {
     || JS('bool', @'# == -Infinity', receiver);
 }
 
-// TODO(ahe): Remove this method when we don't support operator negate.
-negate(receiver) {
-  if (receiver is !num) return UNINTERCEPTED(receiver.negate());
-
-  return JS('num', @'-#', receiver);
-}
-
 round(receiver) {
   if (receiver is !num) return UNINTERCEPTED(receiver.round());