No longer store the compilation-context in WorkItem.

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

Index: pkg/compiler/lib/src/ssa/nodes.dart
diff --git a/pkg/compiler/lib/src/ssa/nodes.dart b/pkg/compiler/lib/src/ssa/nodes.dart
index e64775efe64296756e2029b1fa9082592b824bd5..3fec3f87be2f26e1ffa7cae80cb3b2350ae00415 100644
--- a/pkg/compiler/lib/src/ssa/nodes.dart
+++ b/pkg/compiler/lib/src/ssa/nodes.dart
@@ -164,6 +164,12 @@ class HGraph {
   bool isRecursiveMethod = false;
   bool calledInLoop = false;
   final List<HBasicBlock> blocks = <HBasicBlock>[];
+
+  /// Nodes containing list allocations for which there is a known fixed length.
+  // TODO(sigmund,sra): consider not storing this explicitly here (e.g. maybe
+  // store it on HInstruction, or maybe this can be computed on demand).
+  final Set<HInstruction> allocatedFixedLists = new Set<HInstruction>();
+
   SourceInformation sourceInformation;
 
   // We canonicalize all constants used within a graph so we do not