Fix test...

Author: Tratcher

test/Microsoft.AspNet.PipelineCore.Tests/HeaderDictionaryTests.cs

@@ -20,7 +20,7 @@ public void PropertiesAreAccessible()
                 });
 
             Assert.Equal(1, headers.Count);
-            Assert.Equal(new[] { "Header1" }, headers.Keys);
+            Assert.Equal<string>(new[] { "Header1" }, headers.Keys);
             Assert.True(headers.ContainsKey("header1"));
             Assert.False(headers.ContainsKey("header2"));
             Assert.Equal("Value1", headers["header1"]);