toPrecision is broken

[efergus]

toPrecision outputs the wrong values for some inputs. The function considers the leading "0" in a decimal number to be a significant digit, which it is not.

For example: The toPrecision function is wrong for decimal inputs like 0.222:

Ex:

toPrecision(0.222, 2) // 0.2

Instead, it should be

toPrecision(0.222, 2) // 0.22

[svgeesus]

Hmm, I have noticed this myself on occasion. Thanks for the PR!