Include function names in pretty printer output

This helps make matcher errors and spy strategy mismatch errors easier
to understand in cases where the difference involves expecting one
function but getting a different one.

spec/core/matchers/toEqualSpec.js

@@ -458,9 +458,9 @@ describe('toEqual', function() {
   });
 
   it('reports mismatches between Functions', function() {
-    const actual = { x: function() {} },
-      expected = { x: function() {} },
-      message = 'Expected $.x = Function to equal Function.';
+    const actual = { x: function() {} };
+    const expected = { x: function() {} };
+    const message = "Expected $.x = Function 'x' to equal Function 'x'.";
 
     expect(compareEquals(actual, expected).message).toEqual(message);
   });