Add toStructuredText to ConstantExpression and align method names with ConstantValue

tests/compiler/dart2js/resolver_test.dart

Index: tests/compiler/dart2js/resolver_test.dart
diff --git a/tests/compiler/dart2js/resolver_test.dart b/tests/compiler/dart2js/resolver_test.dart
index f8fb47940a747c0cd2d23621ca0f56075e6e33aa..6067a6c499c69632bef43662aff5cb91a8da0d1b 100644
--- a/tests/compiler/dart2js/resolver_test.dart
+++ b/tests/compiler/dart2js/resolver_test.dart
@@ -1069,12 +1069,12 @@ Future testConstantExpressions() {
       Expect.equals(0, collector.errors.length);
       List<ConstantExpression> constants = elements.constants;
       String constantsText =
-          '[${constants.map((c) => c.getText()).join(', ')}]';
+          '[${constants.map((c) => c.toDartText()).join(', ')}]';
       Expect.equals(expectedConstants.length, constants.length,
           "Expected ${expectedConstants.length} constants for `${constant}` "
           "found $constantsText.");
       for (int index = 0; index < expectedConstants.length; index++) {
-        Expect.equals(expectedConstants[index], constants[index].getText(),
+        Expect.equals(expectedConstants[index], constants[index].toDartText(),
             "Expected ${expectedConstants} for `$constant`, "
             "found $constantsText.");
       }