Thanks @Ashley for the answer.
It means the webview component is not an instance of the browser ( but a crippled one, am I right? ) since my animations run great when loaded directly into the same phone's browser.
I just created an animation with more then 300 frames using EaselJS and even if the error is no longer thrown, the behavior is the same when compiled and run using any of phonegap, appmobi and cocoon. At least that proved it's not a C2 limitation but the phone's OS.
So, will test on Android v. > 2.3.6 and iOS ( hopefully they don't have same limitations ).