Reland #2: Add a short term solution to fix OSX 10.11 system font rendering problems.

Source/platform/mac/VersionUtilMacTest.mm

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #import "config.h"
 #import "platform/mac/VersionUtilMac.h"
 
 #include <AppKit/AppKit.h>
 #include <gtest/gtest.h>
 
 #ifndef NSAppKitVersionNumber10_7
 #define NSAppKitVersionNumber10_7 1138
 #endif
 
 #ifndef NSAppKitVersionNumber10_9
 #define NSAppKitVersionNumber10_9 1265
 #endif
 
 #ifndef NSAppKitVersionNumber10_10
 #define NSAppKitVersionNumber10_10 1343
 #endif
 
 // This number was determined by writing a tiny Cocoa App on 10.10.4.
 #define NSAppKitVersionNumber10_10Max 1348
 
+// This number was measured on OSX 10.11 Beta 15A234d. The 10.11
+// AppKit.framework does not provide an NSAppKitVersionNumber preprocessor
+// definition for OSX 10.11.
+#define NSAppKitVersionNumber10_11Max 1389
+
 // AppKit version is loosely correlated to OSX version. It's still useful as a
 // sanity check in unit tests, though we don't want to rely on it in production
 // code.
 TEST(VersionUtilMac, AppKitVersions)
 {
     if (floor(NSAppKitVersionNumber) <= NSAppKitVersionNumber10_7) {
         EXPECT_TRUE(blink::IsOSLionOrEarlier());
         EXPECT_TRUE(blink::IsOSMavericksOrEarlier());
         EXPECT_FALSE(blink::IsOSMavericks());
+        EXPECT_FALSE(blink::IsOSYosemite());
+        EXPECT_FALSE(blink::IsOSElCapitan());
         return;
     }
 
     if (floor(NSAppKitVersionNumber) < NSAppKitVersionNumber10_9) {
         EXPECT_FALSE(blink::IsOSLionOrEarlier());
         EXPECT_TRUE(blink::IsOSMavericksOrEarlier());
         EXPECT_FALSE(blink::IsOSMavericks());
+        EXPECT_FALSE(blink::IsOSYosemite());
+        EXPECT_FALSE(blink::IsOSElCapitan());
         return;
     }
+
     if (floor(NSAppKitVersionNumber) == NSAppKitVersionNumber10_9) {
         EXPECT_FALSE(blink::IsOSLionOrEarlier());
         EXPECT_TRUE(blink::IsOSMavericksOrEarlier());
         EXPECT_TRUE(blink::IsOSMavericks());
+        EXPECT_FALSE(blink::IsOSYosemite());
+        EXPECT_FALSE(blink::IsOSElCapitan());
         return;
     }
+
     if (floor(NSAppKitVersionNumber) <= NSAppKitVersionNumber10_10Max &&
         floor(NSAppKitVersionNumber) >=  NSAppKitVersionNumber10_10) {
         EXPECT_FALSE(blink::IsOSLionOrEarlier());
         EXPECT_FALSE(blink::IsOSMavericksOrEarlier());
         EXPECT_FALSE(blink::IsOSMavericks());
+        EXPECT_TRUE(blink::IsOSYosemite());
+        EXPECT_FALSE(blink::IsOSElCapitan());
+        return;
+    }
+
+    if (floor(NSAppKitVersionNumber) == NSAppKitVersionNumber10_11Max) {
+        EXPECT_FALSE(blink::IsOSLionOrEarlier());
+        EXPECT_FALSE(blink::IsOSMavericksOrEarlier());
+        EXPECT_FALSE(blink::IsOSMavericks());
+        EXPECT_FALSE(blink::IsOSYosemite());
+        EXPECT_TRUE(blink::IsOSElCapitan());
         return;
     }
 }