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

tests/language/throw1_test.dart

Index: tests/language/throw1_test.dart
diff --git a/tests/language/throw1_test.dart b/tests/language/throw1_test.dart
index d03463a71af205fd4afd3bdc32c7efcf36a1d7d7..b6ace7a773f849595d8664d5522101999bbc0c53 100644
--- a/tests/language/throw1_test.dart
+++ b/tests/language/throw1_test.dart
@@ -33,16 +33,16 @@ class Helper {
       if (j > 0) {
         throw new MyException2("Test for exception being thrown");
       }
-    } catch (MyException3 exception) {
+    } on MyException3 catch (exception) {
       i = 100;
       print(exception.getMessage());
-    } catch (TestException exception) {
+    } on TestException catch (exception) {
       i = 50;
       print(exception.getMessage());
-    } catch (MyException2 exception) {
+    } on MyException2 catch (exception) {
       i = 150;
       print(exception.getMessage());
-    } catch (MyException exception) {
+    } on MyException catch (exception) {
       i = 200;
       print(exception.getMessage());
     } finally {