provide MISSING_RETURN on factory constructors

pkg/analyzer/test/generated/compile_time_error_code_test.dart

Index: pkg/analyzer/test/generated/compile_time_error_code_test.dart
diff --git a/pkg/analyzer/test/generated/compile_time_error_code_test.dart b/pkg/analyzer/test/generated/compile_time_error_code_test.dart
index 34dd9b9745d9de998da40caa7779eae36799ea8d..1bf0dfeb5363e52f8bf70c6bf2878916cd21518c 100644
--- a/pkg/analyzer/test/generated/compile_time_error_code_test.dart
+++ b/pkg/analyzer/test/generated/compile_time_error_code_test.dart
@@ -2209,7 +2209,8 @@ class A {
     Source source = addSource(r'''
 class A {
   int x;
-  factory A(this.x) {}

[scheglov, 2016/04/27 15:52:01]

I think you could replace this with:

factory A(this.x) => null;

...and it would not trigger the new hint.

[srawlins, 2016/04/27 19:52:34]

Great suggestion!

+  A.named() {}
+  factory A(this.x) => new A.named();
 }''');
     computeLibrarySourceErrors(source);
     assertErrors(
@@ -3201,7 +3202,8 @@ class A {
     Source source = addSource(r'''
 int B;
 class A {
-  factory B() {}
+  A.named() {}
+  factory B() => new A.named();
 }''');
     computeLibrarySourceErrors(source);
     assertErrors(
@@ -3212,7 +3214,8 @@ class A {
   void test_invalidFactoryNameNotAClass_notEnclosingClassName() {
     Source source = addSource(r'''
 class A {
-  factory B() {}
+  A.named() {}
+  factory B() => new A.named();
 }''');
     computeLibrarySourceErrors(source);
     assertErrors(
@@ -4736,7 +4739,8 @@ class B extends A {
   void test_nonGenerativeConstructor_explicit() {
     Source source = addSource(r'''
 class A {
-  factory A.named() {}
+  A.named2() {}
+  factory A.named() => new A.named2();
 }
 class B extends A {
   B() : super.named();
@@ -4749,7 +4753,8 @@ class B extends A {
   void test_nonGenerativeConstructor_implicit() {
     Source source = addSource(r'''
 class A {
-  factory A() {}
+  A.named() {}
+  factory A() => new A.named();
 }
 class B extends A {
   B();
@@ -4762,7 +4767,8 @@ class B extends A {
   void test_nonGenerativeConstructor_implicit2() {
     Source source = addSource(r'''
 class A {
-  factory A() {}
+  A.named() {}
+  factory A() => new A.named();
 }
 class B extends A {
 }''');
@@ -5758,8 +5764,10 @@ class A {
   m() {}
 }
 class B extends A {
+  B.named() {}
   factory B() {
     super.m();
+    return new B.named();
   }
 }''');
     computeLibrarySourceErrors(source);