Move all flags to CompilerOptions (first step to stop passing the compiler to

pkg/compiler/lib/src/js_emitter/headers.dart

Index: pkg/compiler/lib/src/js_emitter/headers.dart
diff --git a/pkg/compiler/lib/src/js_emitter/headers.dart b/pkg/compiler/lib/src/js_emitter/headers.dart
index 67fd4a2e70fc9b2c6722397e7e1184fdd42e5749..2d15d111e5515b0a96d261097a78e0911426ddb3 100644
--- a/pkg/compiler/lib/src/js_emitter/headers.dart
+++ b/pkg/compiler/lib/src/js_emitter/headers.dart
@@ -7,7 +7,9 @@ import '../compiler.dart' show Compiler;
 
 String generatedBy(Compiler compiler, {String flavor: ""}) {
   String suffix = '';
-  if (compiler.hasBuildId) suffix = ' version: ${compiler.buildId}';
+  if (compiler.options.hasBuildId) {
+    suffix = ' version: ${compiler.options.buildId}';
+  }
   if (flavor != "") flavor = " ($flavor)";
   return '// Generated by dart2js$flavor, '
       'the Dart to JavaScript compiler$suffix.';