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

tests/language/throw5_test.dart

Index: tests/language/throw5_test.dart
diff --git a/tests/language/throw5_test.dart b/tests/language/throw5_test.dart
index 727eb61a32dea8bb67640ac6831dba40405a3118..d742cf4a33bc5fbedd385bc2ce843654125fb3fd 100644
--- a/tests/language/throw5_test.dart
+++ b/tests/language/throw5_test.dart
@@ -23,13 +23,13 @@ class Helper {
     try {
       int j;
       j = func();
-    } catch (MyException3 exception) {
+    } on MyException3 catch (exception) {
       i = 300;
       print(exception.message_);
-    } catch (MyException2 exception) {
+    } on MyException2 catch (exception) {
       i = 200;
       print(exception.message_);
-    } catch (MyException1 exception) {
+    } on MyException1 catch (exception) {
       i = 100;
       print(exception.message_);
     } finally {
@@ -50,10 +50,10 @@ class Helper {
       if (i > 0) {
         throw new MyException1("Test for MyException1 being thrown");
       }
-    } catch (MyException3 exception) {
+    } on MyException3 catch (exception) {
       i = 300;
       print(exception.message_);
-    } catch (MyException2 exception) {
+    } on MyException2 catch (exception) {
       i = 200;
       print(exception.message_);
     }