Add toStructuredText to ConstantExpression and align method names with ConstantValue

pkg/compiler/lib/src/deferred_load.dart

Index: pkg/compiler/lib/src/deferred_load.dart
diff --git a/pkg/compiler/lib/src/deferred_load.dart b/pkg/compiler/lib/src/deferred_load.dart
index 5ce0d30dcf40ecb663ce66f090b3fa47d950aecc..db578393ae246abbb7b22cbb40dfd0d1994d48ec 100644
--- a/pkg/compiler/lib/src/deferred_load.dart
+++ b/pkg/compiler/lib/src/deferred_load.dart
@@ -887,7 +887,7 @@ class DeferredLoadTask extends CompilerTask {
     _constantToOutputUnit.forEach((ConstantValue value, OutputUnit output) {
       constantMap
           .putIfAbsent(output, () => <String>[])
-          .add(value.toStructuredString());
+          .add(value.toStructuredText());
     });
 
     StringBuffer sb = new StringBuffer();