Update almost all tests (except co19) to use the new try-catch syntax.

tests/language/arithmetic2_test.dart

Index: tests/language/arithmetic2_test.dart
diff --git a/tests/language/arithmetic2_test.dart b/tests/language/arithmetic2_test.dart
index 9f5991977e4255367c158602e7899f3aaafbc600..efe9c387653996e76a7c3318005f3b3d49254c54 100644
--- a/tests/language/arithmetic2_test.dart
+++ b/tests/language/arithmetic2_test.dart
@@ -12,7 +12,7 @@ bool throwsNoSuchMethod(f) {
   try {
     f();
     return false;
-  } catch(NoSuchMethodException e) {
+  } on NoSuchMethodException catch (e) {
     return true;
   }
   return false;
@@ -22,13 +22,13 @@ bool throwsBecauseOfBadArgument(f) {
   try {
     f();
     return false;
-  } catch(NoSuchMethodException e) {
+  } on NoSuchMethodException catch (e) {
     return true;
-  } catch(IllegalArgumentException e) {
+  } on IllegalArgumentException catch (e) {
     return true;
-  } catch(NullPointerException e) {
+  } on NullPointerException catch (e) {
     return true;
-  } catch (TypeError e) {
+  } on TypeError catch (e) {
     // In type checked mode.
     return true;
   }