Make Uri._makeQuery easier to analyze

sdk/lib/core/uri.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of dart.core;
 
 // Frequently used character codes.
 const int _SPACE = 0x20;
 const int _PERCENT = 0x25;
 const int _PLUS = 0x2B;
@@ skipping 2048 matching lines @@
   static String _normalizePath(String path, String scheme, bool hasAuthority) {
     if (scheme.isEmpty && !hasAuthority && !path.startsWith('/')) {
       return _normalizeRelativePath(path);
     }
     return _removeDotSegments(path);
   }
 
   static String _makeQuery(
       String query, int start, int end,
       Map<String, dynamic/*String|Iterable<String>*/> queryParameters) {
-    if (query == null && queryParameters == null) return null;
-    if (query != null && queryParameters != null) {
-      throw new ArgumentError('Both query and queryParameters specified');
+    if (query != null) {
+      if (queryParameters != null) {
+        throw new ArgumentError('Both query and queryParameters specified');
+      }
+      return _normalize(query, start, end, _queryCharTable);
     }
-    if (query != null) return _normalize(query, start, end, _queryCharTable);
+    if (queryParameters == null) return null;
 
     var result = new StringBuffer();
     var separator = "";
 
     void writeParameter(String key, String value) {
       result.write(separator);
       separator = "&";
       result.write(Uri.encodeQueryComponent(key));
       if (value != null && value.isNotEmpty) {
         result.write("=");
@@ skipping 2372 matching lines @@
   int delta = (text.codeUnitAt(start + 4) ^ _COLON) * 3;
   delta |= text.codeUnitAt(start)     ^ 0x64 /*d*/;
   delta |= text.codeUnitAt(start + 1) ^ 0x61 /*a*/;
   delta |= text.codeUnitAt(start + 2) ^ 0x74 /*t*/;
   delta |= text.codeUnitAt(start + 3) ^ 0x61 /*a*/;
   return delta;
 }
 
 /// Helper function returning the length of a string, or `0` for `null`.
 int _stringOrNullLength(String s) => (s == null) ? 0 : s.length;