Add parsing for interface declarations

src/parsing/parser.cc

Index: src/parsing/parser.cc
diff --git a/src/parsing/parser.cc b/src/parsing/parser.cc
index 63fde1dc0770447577db296c756a1412787991cd..b7b757ae3f656469db8700076797abd6fc7f4b7e 100644
--- a/src/parsing/parser.cc
+++ b/src/parsing/parser.cc
@@ -1289,15 +1289,17 @@ Statement* Parser::ParseStatementListItem(bool* ok) {
         return ParseVariableStatement(kStatementListItem, NULL, ok);
       }
       break;
-    case Token::IDENTIFIER: {
+    case Token::IDENTIFIER:
+    case Token::FUTURE_STRICT_RESERVED_WORD: {
       if (!scope_->typed()) break;
       int pos = peek_position();
       if (CheckContextualKeyword(CStrVector("type"))) {
         return ParseTypeAliasDeclaration(pos, ok);
+      } else if (CheckContextualKeyword(CStrVector("interface"))) {
+        return ParseInterfaceDeclaration(pos, ok);
       }
       break;
     }
-    // TODO(nikolaos): interface
     // TODO(nikolaos): ambient
     default:
       break;