Check if it's needed for `toStringWithSourceMap` to produce mapping for eol

[nchevobbe]

We add a mapping for each end of line here:

source-map/lib/source-node.js

Lines 396 to 417 in 4e304db

	if (chunk.charCodeAt(idx) === NEWLINE_CODE) {
	generated.line++;
	generated.column = 0;
	// Mappings end at eol
	if (idx + 1 === length) {
	lastOriginalSource = null;
	sourceMappingActive = false;
	} else if (sourceMappingActive) {
	map.addMapping({
	source: original.source,
	original: {
	line: original.line,
	column: original.column,
	},
	generated: {
	line: generated.line,
	column: generated.column,
	},
	name: original.name,
	});
	}
	} else {

in a project of mine, I overridden this and was not doing this, and the SourceMapConsumer seems to be fine with the sourcemap that is being generated.