SerializeAddon: move test util into seperate file

addons/xterm-addon-serialize/src/SerializeAddon.ts

@@ -412,25 +412,5 @@ export class SerializeAddon implements ITerminalAddon {
       + alternativeScreenContent;
   }
 
-  // this is a util used only for test
-  private static _inspectBuffer(buffer: IBuffer): { x: number, y: number, data: any[][] } {
-    const lines: any[] = [];
-
-    for (let i = 0; i < buffer.length; i++) {
-      /**
-       * Do this intentionally to get content of underlining source
-       */
-      const bufferLine = (buffer.getLine(i)! as any)._line;
-
-      lines.push(JSON.stringify(bufferLine));
-    }
-
-    return {
-      x: buffer.cursorX,
-      y: buffer.cursorY,
-      data: lines
-    };
-  }
-
   public dispose(): void { }
 }