Introduce KernelWorldBuilder

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

Index: pkg/compiler/lib/src/ssa/builder_kernel.dart
diff --git a/pkg/compiler/lib/src/ssa/builder_kernel.dart b/pkg/compiler/lib/src/ssa/builder_kernel.dart
index e6d769fbdd1da5f8f32aad983e662e8537e6df65..e9a837a363e62ceadb974a2d300ad7e0396de5af 100644
--- a/pkg/compiler/lib/src/ssa/builder_kernel.dart
+++ b/pkg/compiler/lib/src/ssa/builder_kernel.dart
@@ -1821,7 +1821,7 @@ class KernelSsaBuilder extends ir.Visitor with GraphBuilder {
     staticSet.value.accept(this);
     HInstruction value = pop();
 
-    var staticTarget = staticSet.target;
+    ir.Member staticTarget = staticSet.target;
     if (staticTarget is ir.Procedure) {
       // Invoke the setter
       _pushStaticInvocation(staticTarget, <HInstruction>[value],
@@ -2465,7 +2465,7 @@ class KernelSsaBuilder extends ir.Visitor with GraphBuilder {
   }
 
   void _pushStaticInvocation(
-      ir.Node target, List<HInstruction> arguments, TypeMask typeMask) {
+      ir.Member target, List<HInstruction> arguments, TypeMask typeMask) {
     HInvokeStatic instruction = new HInvokeStatic(
         astAdapter.getMember(target), arguments, typeMask,
         targetCanThrow: astAdapter.getCanThrow(target, closedWorld));