pathSegTypeAsLetter property should not be lowercase "z"

[cuixiping]

pathSegTypeAsLetter property of a SVGPathSegClosePath object should always be uppercase "Z" (not lowercase "z") like web browsers does.

this.pathSegTypeAsLetter = typeAsLetter=='z'?'Z':typeAsLetter;

[progers]

Thank you for taking the time to file this.

You're absolutely right that this is a bug but I'm leaning towards keeping this bug for pragmatic reasons. Many (all?) folks are using pathseg.js to polyfill the path seg API for Chromium/Blink browsers that removed this feature, and it's helpful to have perfect compatibility with Blink and WebKit.

Maybe we could add a configuration option for blink/webkit compatibility mode vs standards mode or something like that?