src/vs/platform/contextkey/common/contextkey.ts/ContextKeyEqualsExpr/substituteConstants
class ContextKeyEqualsExpr:	public substituteConstants(): ContextKeyExpression | undefined {
		const constantValue = CONSTANT_VALUES.get(this.key);
		if (typeof constantValue === 'boolean') {
			const trueValue = constantValue ? 'true' : 'false';
			return (this.value === trueValue ? ContextKeyTrueExpr.INSTANCE : ContextKeyFalseExpr.INSTANCE);
		}
		return this;
	}