fix(generator): Write URI in sorted order to prevent SHA churn

Author: mhevery

lib/tools/template_cache_generator.dart

@@ -89,7 +89,8 @@ printTemplateCache(Map<String, String> templateKeyMap,
   outSink.write(fileHeader(outputLibrary));
 
   List<Future> reads = <Future>[];
-  templateKeyMap.forEach((uri, templateFile) {
+  templateKeyMap.keys.toList().sort().forEach((uri) {
+    var templateFile = templateKeyMap[uri];
     reads.add(new File(templateFile).readAsString().then((fileStr) {
       fileStr = fileStr.replaceAll('"""', r'\"\"\"');
       String resultUri = uri;