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

pkg/compiler/lib/src/js_backend/codegen/task.dart

Index: pkg/compiler/lib/src/js_backend/codegen/task.dart
diff --git a/pkg/compiler/lib/src/js_backend/codegen/task.dart b/pkg/compiler/lib/src/js_backend/codegen/task.dart
index 89b9aab14652ada935b54768e347625e52fca934..853554fd6c6b6396042476ccd1de79d73804c30f 100644
--- a/pkg/compiler/lib/src/js_backend/codegen/task.dart
+++ b/pkg/compiler/lib/src/js_backend/codegen/task.dart
@@ -322,7 +322,8 @@ class CpsFunctionCompiler implements FunctionCompiler {
 
     treeOptimizationTask.measure(() {
       applyTreePass(new StatementRewriter());
-      applyTreePass(new VariableMerger(minifying: compiler.enableMinification));
+      applyTreePass(new VariableMerger(minifying:
+          compiler.options.enableMinification));
       applyTreePass(new LoopRewriter());
       applyTreePass(new LogicalRewriter());
       applyTreePass(new PullIntoInitializers());