Fixed Function constructor handling when called without arguments.

[VadimZhestikov]

Proposed changes

Fixed Function w/o args called relative an object.

Checklist

Before creating a PR, run through this checklist and mark each as complete:

• I have read the CONTRIBUTING document
• If applicable, I have added tests that prove my fix is effective or that my feature works
• If applicable, I have checked that any relevant tests pass after adding my changes

[xeioex]

I suggest to improve the commit message, something like

Fixed Function constructor handling when called with zero arguments.

Corrected the behavior of Function.constructor() when invoked without arguments relative to an object.

[xeioex]

The commit log message length being less than 67 chars still applies.

[xeioex]

The commit log message length being less than 67 chars still applies.

No changes in filke, only in commit message