Prettify !(x rel-op y) into (x "!rel-op" y) when possible.

lib/compiler/implementation/compile_time_constants.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.
 
 class Constant implements Hashable {
   const Constant();
 
   bool isNull() => false;
   bool isBool() => false;
   bool isTrue() => false;
@@ skipping 61 matching lines @@
 
 class NumConstant extends PrimitiveConstant {
   abstract num get value();
   const NumConstant();
   bool isNum() => true;
 }
 
 class IntConstant extends NumConstant {
   final int value;
   factory IntConstant(int value) {
-    switch(value) {
+    switch (value) {
       case 0: return const IntConstant._internal(0);
       case 1: return const IntConstant._internal(1);
       case 2: return const IntConstant._internal(2);
       case 3: return const IntConstant._internal(3);
       case 4: return const IntConstant._internal(4);
       case 5: return const IntConstant._internal(5);
       case 6: return const IntConstant._internal(6);
       case 7: return const IntConstant._internal(7);
       case 8: return const IntConstant._internal(8);
       case 9: return const IntConstant._internal(9);
@@ skipping 577 matching lines @@
         // TODO(lrn): Consider whether all codes above 0x7f really need to
         // be escaped. We build a Dart string here, so it should be a literal
         // stage that converts it to, e.g., UTF-8 for a JS interpreter.
         if (code < 0x20) {
           buffer.add(@'\x');
           if (code < 0x10) buffer.add('0');
           buffer.add(code.toRadixString(16));
         } else if (code >= 0x80) {
           if (code < 0x100) {
             buffer.add(@'\x');
-            buffer.add(code.toRadixString(16));
           } else {
             buffer.add(@'\u');
             if (code < 0x1000) {
               buffer.add('0');
             }
-            buffer.add(code.toRadixString(16));
           }
+          buffer.add(code.toRadixString(16));
         } else {
-          buffer.add(new String.fromCharCodes(<int>[code]));
+          buffer.addCharCode(code);
         }
       }
     }
   }
 
   String getJsConstructor(ClassElement element) {
     return compiler.namer.isolatePropertyAccess(element);
   }
 }
 
@@ skipping 447 matching lines @@
       Constant fieldValue = fieldValues[field];
       if (fieldValue === null) {
         // Use the default value.
         fieldValue = compiler.compileVariable(field);
       }
       jsNewArguments.add(fieldValue);
     });
     return jsNewArguments;
   }
 }