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

tests/language/rethrow_test.dart

Index: tests/language/rethrow_test.dart
diff --git a/tests/language/rethrow_test.dart b/tests/language/rethrow_test.dart
index 20ebf18efe2a7bc3dee1ee930c54e460dc65aeee..021a0fce58a316608bcc8bbac2508d3d39e3cf97 100644
--- a/tests/language/rethrow_test.dart
+++ b/tests/language/rethrow_test.dart
@@ -25,15 +25,15 @@ class RethrowTest {
         try {
           throwException();
           Expect.fail("Should have thrown an exception");
-        } catch (var e) {
+        } catch (e) {
           Expect.equals(true, e === currentException);
           throw;
           Expect.fail("Should have thrown an exception");
         }
-      } catch (OtherException e) {
+      } on OtherException catch (e) {
         Expect.fail("Should not have caught OtherException");
       }
-    } catch (var e) {
+    } catch (e) {
       Expect.equals(true, e === currentException);
     }
   }
@@ -43,12 +43,12 @@ class RethrowTest {
       try {
         throwException();
         Expect.fail("Should have thrown an exception");
-      } catch (var e) {
+      } catch (e) {
         Expect.equals(true, e === currentException);
         throw;
         Expect.fail("Should have thrown an exception");
       }
-    } catch (var e) {
+    } catch (e) {
       Expect.equals(true, e === currentException);
     }
   }