Rename Constant to ConstantValue and ConstExp to ConstantExpression.

sdk/lib/_internal/compiler/implementation/ssa/codegen_helpers.dart

Index: sdk/lib/_internal/compiler/implementation/ssa/codegen_helpers.dart
diff --git a/sdk/lib/_internal/compiler/implementation/ssa/codegen_helpers.dart b/sdk/lib/_internal/compiler/implementation/ssa/codegen_helpers.dart
index c92fd60967a70994d0e214bbaa79933d28310897..abc6c8658399fa7253d83202f82b0d3e298e106e 100644
--- a/sdk/lib/_internal/compiler/implementation/ssa/codegen_helpers.dart
+++ b/sdk/lib/_internal/compiler/implementation/ssa/codegen_helpers.dart
@@ -120,7 +120,7 @@ class SsaInstructionSelection extends HBaseVisitor {
           // TODO(15933): Make automatically generated property extraction
           // closures work with the dummy receiver optimization.
           if (!selector.isGetter) {
-            Constant constant = new DummyConstant(
+            ConstantValue constant = new DummyConstantValue(
                 receiverArgument.instructionType);
             HConstant dummy = graph.addConstant(constant, compiler);
             receiverArgument.usedBy.remove(node);