Don't autocorrect BigDecimal with float when precision is specified

[eugeneius]

The precision argument to BigDecimal() is ignored unless the value is a float or rational. Converting the value from a float to a string when a precision is specified changes the result.

$ ruby -rbigdecimal -e "puts BigDecimal(3.14, 1)"
0.3e1

$ ruby -rbigdecimal -e "puts BigDecimal('3.14', 1)"
0.314e1

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[koic]

This looks good! Can you rebase with the latest master branch?

[eugeneius]

Rebased ✅

[koic]

Thanks!