auto merge of #4884 : pcwalton/rust/pretty-print-new-impl-syntax, r=pcwalton

r? @brson

src/test/run-pass/class-attributes-1.rs

@@ -14,7 +14,7 @@ struct cat {
     name: ~str,
 }
 
-impl cat: Drop {
+impl Drop for cat {
     #[cat_dropper]
     fn finalize(&self) { error!("%s landed on hir feet" , self . name); }
 }

src/test/run-pass/method-attributes.rs

@@ -19,7 +19,7 @@ trait frobable {
 }
 
 #[int_frobable]
-impl int: frobable {
+impl frobable for int {
     #[frob_attr1]
     fn frob() {
         #[frob_attr2];