fix(runtime): start timer handles at 1

[kushagrabist]

This Pull Request fixes/closes #5378.

It changes the following:

• Start timer handles at 1 instead of 0.
• Reserve 0 for the "no timer scheduled" sentinel value returned by setTimeout() and setInterval().
• Ensure timer handles are positive integers, matching the HTML Timers specification and avoiding collisions with the sentinel value.

[jedel1043]

Duplicate of #5379