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

tests/corelib/string_base_vm_test.dart

Index: tests/corelib/string_base_vm_test.dart
diff --git a/tests/corelib/string_base_vm_test.dart b/tests/corelib/string_base_vm_test.dart
index d96702e94f3fe490cc72cb4fe7dcb0b01735f93b..fef8b04c5655b81ac6fa8abfb81020965c83f4b7 100644
--- a/tests/corelib/string_base_vm_test.dart
+++ b/tests/corelib/string_base_vm_test.dart
@@ -48,14 +48,14 @@ class StringBaseTest {
     Expect.equals(s, s3);
     try {
       String s4 = new String.fromCharCodes([0.0]);
-    } catch (IllegalArgumentException ex) {
+    } on IllegalArgumentException catch (ex) {
       exception_caught = true;
     }
     Expect.equals(true, exception_caught);
     exception_caught = false;
     try {
       String s4 = new String.fromCharCodes([-1]);
-    } catch (IllegalArgumentException ex) {
+    } on IllegalArgumentException catch (ex) {
       exception_caught = true;
     }
     Expect.equals(true, exception_caught);
@@ -68,14 +68,14 @@ class StringBaseTest {
     bool exception_caught = false;
     try {
       s.substring(5, 12);
-    } catch (IndexOutOfRangeException ex) {
+    } on IndexOutOfRangeException catch (ex) {
       exception_caught = true;
     }
     Expect.equals(true, exception_caught);
     exception_caught = false;
     try {
       s.substring(5, 4);
-    } catch (IndexOutOfRangeException ex) {
+    } on IndexOutOfRangeException catch (ex) {
       exception_caught = true;
     }
     Expect.equals(true, exception_caught);