Cocoa: Fix OpenGL rendering not being displayed

Fix based on information provided by @rcgordon.

Fixes #1334.
Closes #1346.

README.md

@@ -271,6 +271,8 @@ information on what to include when reporting a bug.
 - [Cocoa] Bugfix: Window was resized twice when entering full screen (#1085)
 - [Cocoa] Bugfix: Duplicate size events were not filtered (#1085)
 - [Cocoa] Bugfix: Event polling did not initialize AppKit if necessary (#1218)
+- [Cocoa] Bugfix: OpenGL rendering was not initially visible on 10.14
+                  (#1334,#1346)
 - [WGL] Added support for `WGL_EXT_colorspace` for OpenGL ES contexts
 - [WGL] Added support for `WGL_ARB_create_context_no_error`
 - [GLX] Added support for `GLX_ARB_create_context_no_error`

src/cocoa_window.m

@@ -476,6 +476,14 @@ static const NSRange kEmptyRange = { NSNotFound, 0 };
     return YES;
 }
 
+- (void)updateLayer
+{
+    if (window->context.client != GLFW_NO_API)
+        [window->context.nsgl.object update];
+
+    _glfwInputWindowDamage(window);
+}
+
 - (id)makeBackingLayer
 {
     if (window->ns.layer)