src/vs/platform/contextkey/browser/contextKeyService.ts/AbstractContextKeyService/removeContext
class AbstractContextKeyService:	public removeContext(key: string): void {
		if (this._isDisposed) {
			return;
		}
		if (this.getContextValuesContainer(this._myContextId).removeValue(key)) {
			this._onDidChangeContext.fire(new SimpleContextKeyChangeEvent(key));
		}
	}