Use new try-catch syntax in runtime/, tools/, and utils/.

runtime/lib/double.dart

Index: runtime/lib/double.dart
diff --git a/runtime/lib/double.dart b/runtime/lib/double.dart
index bb3ef1ad63db977d23b105d5b3f62c706c8dfa78..c69240c981a2b26b9d91d517e697e2111becdf8c 100644
--- a/runtime/lib/double.dart
+++ b/runtime/lib/double.dart
@@ -8,7 +8,7 @@ class Double implements double {
   int hashCode() {
     try {
       return toInt();
-    } catch (FormatException e) {
+    } on FormatException catch (e) {
       return 0;
     }
   }