fixes #27586, prefer context type in generic inference

pkg/analyzer/test/generated/strong_mode_test.dart

Index: pkg/analyzer/test/generated/strong_mode_test.dart
diff --git a/pkg/analyzer/test/generated/strong_mode_test.dart b/pkg/analyzer/test/generated/strong_mode_test.dart
index 783b462616b95a008052c4bdf2b34804f196ce59..550e4a651492d39bab309e007cba9995a501c151 100644
--- a/pkg/analyzer/test/generated/strong_mode_test.dart
+++ b/pkg/analyzer/test/generated/strong_mode_test.dart
@@ -1452,11 +1452,28 @@ class D<S> {
   }
 
   void test_genericFunction_upwardsAndDownwards() {
-    // Regression tests for https://github.com/dart-lang/sdk/issues/27151.
+    // Regression tests for https://github.com/dart-lang/sdk/issues/27586.
     resolveTestUnit(r'List<num> x = [1, 2];');
-    expectInitializerType('x', 'List<int>');
+    expectInitializerType('x', 'List<num>');
   }
 
+  void test_genericFunction_upwardsAndDownwards_Object() {

[Leaf, 2016/11/30 05:24:30]

Can you add a version of this using generic methods and one using constructors,
since those go through somewhat different paths in places?

+    // Regression tests for https://github.com/dart-lang/sdk/issues/27625.
+    resolveTestUnit(r'''
+List<Object> aaa = [];
+List<Object> bbb = [1, 2, 3];
+List<Object> ccc = [null];
+List<Object> ddd = [1 as dynamic];
+List<Object> eee = [new Object()];

[Leaf, 2016/11/30 05:24:29]

Do we have any test cases for inference which uses the new partial contexts?

+    ''');
+    expectInitializerType('aaa', 'List<Object>');
+    expectInitializerType('bbb', 'List<Object>');
+    expectInitializerType('ccc', 'List<Object>');
+    expectInitializerType('ddd', 'List<Object>');
+    expectInitializerType('eee', 'List<Object>');
+  }
+
+
   void test_genericMethod() {
     resolveTestUnit(r'''
 class C<E> {