Use template string to shorten code.

Author: Tien Nguyen

src/harness/fourslash.ts

@@ -2172,7 +2172,7 @@ module FourSlash {
  for (let highlight of highlightSpans) {
  if (highlight && highlight.textSpan.start === start && ts.textSpanEnd(highlight.textSpan) === end) {
  if (typeof kind !== "undefined" && highlight.kind !== kind) {
- this.raiseError('verifyDocumentHighlightsAtPositionListContains failed - item "kind" value does not match, actual: ' + highlight.kind + ', expected: ' + kind + '.');
+ this.raiseError(`verifyDocumentHighlightsAtPositionListContains failed - item "kind" value does not match, actual: ${highlight.kind}, expected: ${kind}.`);
  }
  return;
  }