Pass context class directly to KernelSsaBuilder

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

Index: pkg/compiler/lib/src/ssa/rasta_ssa_builder_task.dart
diff --git a/pkg/compiler/lib/src/ssa/rasta_ssa_builder_task.dart b/pkg/compiler/lib/src/ssa/rasta_ssa_builder_task.dart
index 6968f0503900e3c5d65281f6f448f31d3f1be7a7..61c857651ac4672816c55ced905b736c432ee2fc 100644
--- a/pkg/compiler/lib/src/ssa/rasta_ssa_builder_task.dart
+++ b/pkg/compiler/lib/src/ssa/rasta_ssa_builder_task.dart
@@ -34,6 +34,7 @@ class RastaSsaBuilderTask extends SsaAstBuilderBase {
           work.resolvedAst, kernel.nodeToAst, kernel.nodeToElement);
       KernelSsaBuilder builder = new KernelSsaBuilder(
           element,
+          element.contextClass,
           backend.compiler,
           astAdapter,
           closedWorld,