Clean up deferred checks in Kernel.

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 81e533eb925593ed35df18005c2eca938e440567..87e8380bda2d3e0d3d0d7b2a074b566b8068c002 100644
--- a/pkg/compiler/lib/src/ssa/builder_kernel.dart
+++ b/pkg/compiler/lib/src/ssa/builder_kernel.dart
@@ -596,11 +596,9 @@ class KernelSsaBuilder extends ir.Visitor with GraphBuilder {
   void visitCheckLibraryIsLoaded(ir.CheckLibraryIsLoaded checkLoad) {
     HInstruction prefixConstant = graph.addConstantString(
         new DartString.literal(checkLoad.import.name), closedWorld);
+    var prefixElement = astAdapter.getElement(checkLoad.import);
     HInstruction uriConstant = graph.addConstantString(
-        new DartString.literal(compiler.deferredLoadTask.getImportDeferName(
-            // TODO(efortuna): Source information.
-            null,
-            astAdapter.getElement(checkLoad.import))),
+        new DartString.literal(prefixElement.deferredImport.uri.toString()),
         closedWorld);
     _pushStaticInvocation(astAdapter.checkDeferredIsLoaded,
         [prefixConstant, uriConstant], astAdapter.checkDeferredIsLoadedType);