Updates dartc to recognize 'default' keyword on interface and updated factory method syntax

tests/stub-generator/src/MintMakerPromiseWithStubsTest-generatedTest.dart

Index: tests/stub-generator/src/MintMakerPromiseWithStubsTest-generatedTest.dart
diff --git a/tests/stub-generator/src/MintMakerPromiseWithStubsTest-generatedTest.dart b/tests/stub-generator/src/MintMakerPromiseWithStubsTest-generatedTest.dart
index 24a9bcebcecd794e98c42b6b112b298f41d27fbc..667281fe23b68a745f3676a948ff48c0abc95b0c 100644
--- a/tests/stub-generator/src/MintMakerPromiseWithStubsTest-generatedTest.dart
+++ b/tests/stub-generator/src/MintMakerPromiseWithStubsTest-generatedTest.dart
@@ -133,7 +133,7 @@ class Purse$Dispatcher$Isolate extends Isolate {
     });
   }
 }
-interface Mint factory MintImpl {
+interface Mint default MintImpl {
 
   Mint();
 
@@ -141,7 +141,7 @@ interface Mint factory MintImpl {
 
 }
 
-interface Purse factory PurseImpl {
+interface Purse default PurseImpl {
 
   Purse();