Add ATI Radeon HD 2600 XT on Mac to the software rendering list....

chrome/browser/resources/software_rendering_list.json

 // Determines whether certain gpu-related features are blacklisted or not.
 // A valid software_rendering_list.json file are in the format of
 // {
 //   "version": "x.y",
 //   "entries": [
 //     { // entry 1
 //     },
 //     ...
 //     { // entry n
 //     }
@@ skipping 20 matching lines @@
 // following values: "=", "<", "<=", ">", ">=", "any", "between".  "number2" is
 // only used if "op" is "between".  "number" is used for all "op" values except
 // "any". "number" and "number2" are in the format of x, x.x, x.x.x, ect.
 //
 // STRING includes "op" and "value".  "op" can be any of the following values:
 // "contains", "beginwith", "endwith", "=".  "value" is a string.
 
 {
   "name": "software rendering list",
   // Please update the version number whenever you change this file.
-  "version": "1.1",
+  "version": "1.2",
   "entries": [
     { // ATI Radeon X1900 on Mac, BUGWEBKIT=47028
       "id": "1",
       "os": {
         "type": "macosx"
       },
       "vendor_id": "0x1002",
       "device_id": "0x7249",
       "blacklist": [
         "webgl"
@@ skipping 104 matching lines @@
     { // NVIDIA GeForce 7300 GT on Mac, BUG=73794
       "id": "10",
       "os": {
         "type": "macosx"
       },
       "vendor_id": "0x10de",
       "device_id": "0x0393",
       "blacklist": [
         "webgl"
       ]
+    },
+    { // ATI Radeon HD2600 XT on Mac, BUG=68859
+      "id": "11",
+      "os": {
+        "type": "macosx"
+      },
+      "vendor_id": "0x1002",
+      "device_id": "0x9588",
+      "blacklist": [
+        "webgl",
+        "accelerated_compositing"
+      ]
     }
   ]
 }