Const enum over magic number

addons/addon-fit/src/FitAddon.ts

@@ -22,6 +22,11 @@ interface ITerminalDimensions {
 const MINIMUM_COLS = 2;
 const MINIMUM_ROWS = 1;
 
+// Must remain in sync with the value in core's viewport
+const enum Constants {
+  DEFAULT_SCROLL_BAR_WIDTH = 14
+}
+
 export class FitAddon implements ITerminalAddon , IFitApi {
   private _terminal: Terminal | undefined;
 
@@ -66,7 +71,7 @@ export class FitAddon implements ITerminalAddon , IFitApi {
 
     const scrollbarWidth = (this._terminal.options.scrollback === 0
       ? 0
-      : (this._terminal.options.overviewRulerWidth || 14));
+      : (this._terminal.options.overviewRulerWidth || Constants.DEFAULT_SCROLL_BAR_WIDTH));
 
     const parentElementStyle = window.getComputedStyle(this._terminal.element.parentElement);
     const parentElementHeight = parseInt(parentElementStyle.getPropertyValue('height'));