dygraphs: add missing getRowForX() definition (#41335)
dygraphs: add missing getRowForX() definition (#41335)

* dygraphs: add missing getRowForX() definition

Documentation: http://dygraphs.com/jsdoc/symbols/Dygraph.html#getRowForX
Source code: https://github.com/danvk/dygraphs/blob/27cee3f7233fbbbeed31f0cf03ea81bf92555b18/src/dygraph.js#L3345-L3372

* dygraphs: Drop type annotations from .d.ts's JSDoc

danvk: "At best they are duplicative and at worst they disagree (as in this case)."

georgemarshall/DefinitelyTyped,mcliment/DefinitelyTyped,dsebastien/DefinitelyTyped,georgemarshall/DefinitelyTyped,georgemarshall/DefinitelyTyped,dsebastien/DefinitelyTyped,georgemarshall/DefinitelyTyped,markogresak/DefinitelyTyped