Revert "Adjusts dart2js backend to handle method type arguments."

pkg/compiler/lib/src/ssa/optimize.dart

Index: pkg/compiler/lib/src/ssa/optimize.dart
diff --git a/pkg/compiler/lib/src/ssa/optimize.dart b/pkg/compiler/lib/src/ssa/optimize.dart
index c7fb15d300522e968e5194f378dbd5b6e052c549..a4ee03951d52a675688e9ffe70fc261d91960935 100644
--- a/pkg/compiler/lib/src/ssa/optimize.dart
+++ b/pkg/compiler/lib/src/ssa/optimize.dart
@@ -780,8 +780,6 @@ class SsaInstructionSimplifier extends HBaseVisitor
     return inputType.isInMask(checkedType, classWorld) ? input : node;
   }
 
-  HInstruction removeCheck(HCheck node) => node.checkedInput;
-
   VariableElement findConcreteFieldForDynamicAccess(
       HInstruction receiver, Selector selector) {
     TypeMask receiverType = receiver.instructionType;