Indeed, moving ccConfig outside of DOMContentLoaded makes it more stable on IE 10. It appears to be variable order issue with different javascript engines.
On iOS 7, with sample tests and moving to single engine, the following errors show:
[Error] Failed to load resource (BaseTestLayer.js, line 0)
[Error] ReferenceError: Can’t find variable: BaseTestLayer
global code (SchedulerTest.js, line 32)
[Error] ReferenceError: Can’t find variable: BaseTestLayer
global code (ActionsTest.js, line 45)
[Error] ReferenceError: Can’t find variable: BaseTestLayer
global code (TileMapTest.js, line 33)
[Error] ReferenceError: Can’t find variable: BaseTestLayer
global code (TransitionsTest.js, line 186)
[Error] ReferenceError: Can’t find variable: BaseTestLayer
global code (DrawPrimitivesTest.js, line 34)
[Error] ReferenceError: Can’t find variable: BaseTestLayer
global code (ParticleTest.js, line 169)
[Error] ReferenceError: Can’t find variable: BaseTestLayer
global code (ProgressActionsTest.js, line 28)
[Error] ReferenceError: Can’t find variable: BaseTestLayer
global code (LayerTest.js, line 45)
[Error] ReferenceError: Can’t find variable: BaseTestLayer
global code (SpriteTest.js, line 55)
[Error] ReferenceError: Can’t find variable: BaseTestLayer
global code (CocosNodeTest.js, line 35)
[Error] ReferenceError: Can’t find variable: BaseTestLayer
global code (RenderTextureTest.js, line 28)
[Error] ReferenceError: Can’t find variable: BaseTestLayer
global code (ActionManagerTest.js, line 40)
[Error] ReferenceError: Can’t find variable: BaseTestLayer
global code (EaseActionsTest.js, line 45)
[Error] ReferenceError: Can’t find variable: BaseTestLayer
global code (ParallaxTest.js, line 30)
[Error] ReferenceError: Can’t find variable: BaseTestLayer
global code (FontTest.js, line 87)
[Error] ReferenceError: Can’t find variable: BaseTestLayer
global code (LabelTest.js, line 52)
[Error] ReferenceError: Can’t find variable: BaseTestLayer
global code (UnitTest.js, line 33)
[Error] ReferenceError: Can’t find variable: BaseTestLayer
global code (SysTest.js, line 33)
[Error] ReferenceError: Can’t find variable: BaseTestLayer
global code (FileUtilsTest.js, line 33)
[Error] ReferenceError: Can’t find variable: BaseTestLayer
global code (EffectsTest.js, line 33)
[Error] ReferenceError: Can’t find variable: BaseTestLayer
global code (ClippingNodeTest.js, line 35)
[Error] ReferenceError: Can’t find variable: BaseTestLayer
global code (OpenGLTest.js, line 50)
[Error] ReferenceError: Can’t find variable: BaseTestLayer
global code (ArmatureTest.js, line 103)
[Error] ReferenceError: Can’t find variable: BaseTestLayer
global code (ChipmunkTest.js, line 65)
[Log] Cocos2d-html5-v2.2 (Cocos2d-html5-v2.2.min.js, line 23)
[Error] TypeError: ‘undefined’ is not a constructor (evaluating ‘new ActionManagerTestScene()’)
testScene (tests-main.js, line 208)
(anonymous function) (tests-main.js, line 160)
*complete
*updatePercent (Cocos2d-html5-v2.2.min.js, line 1324)
_preload (Cocos2d-html5-v2.2.min.js, line 1321)
(anonymous function) (Cocos2d-html5-v2.2.min.js, line 1323)
the last error line is due to pressing ActionManager Test … refresh the page then it runs with a slight error
[Error] ReferenceError: Can’t find variable: cp
global code (ChipmunkTest.js, line 691)
[Log] Cocos2d-html5-v2.2 (Cocos2d-html5-v2.2.min.js, line 23)