Fix issues with doc comments being missing from some declarations

std/d/ast.d

@@ -787,6 +787,7 @@ public:
     }
     /** */ Token[] identifiers;
     /** */ Initializer[] initializers;
+    /** */ string comment;
     mixin OpEquals;
 }
 

std/d/parser.d

@@ -6051,6 +6051,7 @@ q{doStuff(5)}c;
         }
 
         node.type = type is null ? parseType() : type;
+        node.comment = comment;
 
         Declarator[] declarators;
         while(true)
@@ -6073,7 +6074,7 @@ q{doStuff(5)}c;
 //        }
 //        else
         {
-            expect(tok!";");
+            if (expect(tok!";") is null) return null;
             return node;
         }
     }