Add summary support for ConstructorElement.nameEnd and .periodOffset.

pkg/analyzer/lib/src/summary/summarize_elements.dart

Index: pkg/analyzer/lib/src/summary/summarize_elements.dart
diff --git a/pkg/analyzer/lib/src/summary/summarize_elements.dart b/pkg/analyzer/lib/src/summary/summarize_elements.dart
index 0a011621644f058ab8462a967ce467f3c6a1590d..7e19b675a957ef1103fbdf5a7b391e3a638c40a9 100644
--- a/pkg/analyzer/lib/src/summary/summarize_elements.dart
+++ b/pkg/analyzer/lib/src/summary/summarize_elements.dart
@@ -556,7 +556,12 @@ class _CompilationUnitSerializer {
     UnlinkedExecutableBuilder b = new UnlinkedExecutableBuilder();
     b.name = executableElement.name;
     b.nameOffset = executableElement.nameOffset;
-    if (executableElement is! ConstructorElement) {
+    if (executableElement is ConstructorElement) {
+      if (executableElement.name.isNotEmpty) {
+        b.nameEnd = executableElement.nameEnd;
+        b.periodOffset = executableElement.periodOffset;
+      }
+    } else {
       if (!executableElement.hasImplicitReturnType) {
         b.returnType = serializeTypeRef(
             executableElement.type.returnType, executableElement);