Remove the limit of number of commands per extension, but keep the limit of 4 shortcuts per extensi…

chrome/test/data/extensions/manifest_tests/command_too_many.json

 {
-  "name": "Command test - too many commands",
+  "name": "Command test - too many commands with shortcuts",
   "manifest_version": 2,
   "version": "2",
   "commands": {
     "feature1": {
       "suggested_key": "Ctrl+A",
       "description": "feature1"
     },
     "feature2": {
       "suggested_key": "Ctrl+B",
       "description": "feature2"
     },
     "feature3": {
       "suggested_key": "Ctrl+C",
       "description": "feature3"
     },
     "feature4": {
       "suggested_key": "Ctrl+D",
       "description": "feature4"
     },
     "feature5": {
       "suggested_key": "Ctrl+E",
       "description": "feature5"
     }
   }
- }
+}