perf(drag-drop): use narrower check for touch events (#16082)
perf(drag-drop): use narrower check for touch events (#16082)

We use the `isTouchEvent` any time we need to normalize something between touch and mouse events which happens for every pixel that the user has dragged. These changes switch to using direct comparison, rather than `startsWith`, which should be slightly faster since there's a narrow set of touch event types.
josephperrott/material2,crisbeto/material2,Jefiozie/material2,mmalerba/material2,DevVersion/material2,Jefiozie/material2,Jefiozie/material2,angular/components,angular/components,jelbourn/material2,angular/components,angular/components,Jefiozie/material2,jelbourn/material2,Jefiozie/material2,josephperrott/material2,josephperrott/material2,DevVersion/material2,andrewseguin/material2,mmalerba/material2,andrewseguin/material2,jelbourn/material2,mmalerba/material2,DevVersion/material2,josephperrott/material2,crisbeto/material2,josephperrott/material2,jelbourn/material2,DevVersion/material2,crisbeto/material2,mmalerba/material2,mmalerba/material2,crisbeto/material2,DevVersion/material2,andrewseguin/material2,andrewseguin/material2,jelbourn/material2,andrewseguin/material2