dart2js cps: Fix some analyzer hints in the CPS backend.

pkg/compiler/lib/src/cps_ir/cps_ir_builder.dart

Index: pkg/compiler/lib/src/cps_ir/cps_ir_builder.dart
diff --git a/pkg/compiler/lib/src/cps_ir/cps_ir_builder.dart b/pkg/compiler/lib/src/cps_ir/cps_ir_builder.dart
index a80f2f73d0b964c72671e2f6a9ac80db11d1bac3..76b2d22836b48fcda12ea0bdc3d66493d1bc2bfb 100644
--- a/pkg/compiler/lib/src/cps_ir/cps_ir_builder.dart
+++ b/pkg/compiler/lib/src/cps_ir/cps_ir_builder.dart
@@ -653,14 +653,6 @@ class IrBuilder {
     return primitive;
   }
 
-  ir.Primitive _continueWithExpression(ir.Expression build(ir.Continuation k)) {
-    ir.Parameter v = new ir.Parameter(null);
-    ir.Continuation k = new ir.Continuation([v]);
-    ir.Expression expression = build(k);
-    add(new ir.LetCont(k, expression));
-    return v;
-  }
-
   ir.Primitive _buildInvokeStatic(Element element,
                                   Selector selector,
                                   List<ir.Primitive> arguments,