Fix hints reported by analyzer.

pkg/compiler/lib/src/dart2js.dart

Index: pkg/compiler/lib/src/dart2js.dart
diff --git a/pkg/compiler/lib/src/dart2js.dart b/pkg/compiler/lib/src/dart2js.dart
index cb39e7802767cb2599d7b35d9fd9d70d1954dc08..812460a3e2340660dba8be384383c923f82d5182 100644
--- a/pkg/compiler/lib/src/dart2js.dart
+++ b/pkg/compiler/lib/src/dart2js.dart
@@ -122,7 +122,6 @@ Future<api.CompilationResult> compile(List<String> argv) {
   Uri resolutionOutput = currentDirectory.resolve('out.data');
   bool allowNativeExtensions = false;
   bool trustTypeAnnotations = false;
-  bool trustJSInteropTypeAnnotations = false;
   bool checkedMode = false;
   List<String> hints = <String>[];
   bool verbose;
@@ -243,7 +242,6 @@ Future<api.CompilationResult> compile(List<String> argv) {
   }
 
   void setTrustJSInteropTypeAnnotations(String argument) {
-    trustJSInteropTypeAnnotations = true;
     implyCompilation(argument);
   }