ElementTagNameMap has wrong case for camelCase SVG elements

[HolgerJeromin]

TypeScript Version: master

Code

var svgEle = document.createElementNS('http://www.w3.org/2000/svg', 'svg');
var linGrad = document.createElementNS('http://www.w3.org/2000/svg', 'linearGradient');
svgEle.appendChild(linGrad);

// typescript SVGLinearGradientElement, Browser null (Tested with Chrome and IE11)
var resultNull = svgEle.querySelector('lineargradient'); 

// typescript Element,  Browser SVGLinearGradientElement
var resultOk = svgEle.querySelector('linearGradient'); 

Expected behavior:
.querySelector('linearGradient')
should return a SVGLinearGradientElement

Actual behavior:
The *TagNameMap maps the wrong case to the SvgElement type
https://github.com/Microsoft/TypeScript/blob/02e79849ef7259a1985391d85faea1cd6d86c3d0/lib/lib.d.ts#L19129

Probably effected:
clipPath, componentTransferFunction, feBlend, feColorMatrix, feComponentTransfer, feComposite, feConvolveMatrix, feDiffuseLighting, feDisplacementMap, feDistantLight, feFlood, feFuncA, feFuncB, feFuncG, feFuncR, feGaussianBlur, feImage, feMerge, feMergeNode, feMorphology, feOffset, fePointLight, feSpecularLighting, feSpotLight, feTile, feTurbulence, foreignObject, linearGradient, radialGradient, textContent, textPath, textPositioning

[mhegazy]

PRs welcomed. You can find more information about contributing lib.d.ts fixes at https://github.com/Microsoft/TypeScript/blob/master/CONTRIBUTING.md#contributing-libdts-fixes.

[variousauthors]

It appears that all of the entries in the SVGElementTagNameMap interface are lowercase, rather than camelcase, where as in the spec they are camelcase. There was an issue regarding the camelcase svg tags in the w3c repo that may shed some insight into this issue: w3c/svgwg#161

It looks like the tagnames are case insensitive, so you can use <linearGradient> or <lineargradient> and it will be fine, but the methods are case sensitive?