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

tests/language/double_to_string_as_fixed_test.dart

Index: tests/language/double_to_string_as_fixed_test.dart
diff --git a/tests/language/double_to_string_as_fixed_test.dart b/tests/language/double_to_string_as_fixed_test.dart
index faaeb2bd58f28480261ccb1ad2e0e06ea014b0c5..fae036365ca72875ccfe97e60f839533cc454173 100644
--- a/tests/language/double_to_string_as_fixed_test.dart
+++ b/tests/language/double_to_string_as_fixed_test.dart
@@ -89,7 +89,7 @@ class ToStringAsFixedTest {
       bool thrown = false;
       try {
         0.0.toStringAsFixed(-1);
-      } catch (final e) {
+      } catch (e) {
         thrown = true;
       }
       Expect.equals(true, thrown);
@@ -98,7 +98,7 @@ class ToStringAsFixedTest {
       bool thrown = false;
       try {
         0.0.toStringAsFixed(22);
-      } catch (final e) {
+      } catch (e) {
         thrown = true;
       }
       Expect.equals(true, thrown);