Inconsistent behavior between LabelTTFCanvas and LabelTTFWebGL

[luisparravicini]

Changing the text of a TTF label, the label's dimension is updated right away in LabelTTFCanvas but on the next visit made to LabelTTFWebGL.

I think both should do the same, or at least specify this difference in the documentation (maybe it's somewhere in the docs, haven't found it).

setString In LabelTTFCanvas:

// Force update
if (this._string.length > 0)
    this._updateTTF();

in LabelTTFWebGL:

// Force update
this._needUpdateTexture = true;

[dingpinglv]

Thanks for your feedback, Luis.

It's expensive for performance in LabelTTFWebGL when it calls _updateTexture(), so we add a _needUpdateTexture flag to save the state.

You're right that the behavior of LabelTTFCanvas and LabelTTFWebGL need to be consistent. We will modify LabelTTFCanvas to make it as a consistent behavior.