Number filter with exponentially small numbers without fractionSize

[bobrik]

Currently, if fractionSize is not passed, for small numbers like 1e-50 number filter produces string 1e-50.

It happens because fractionSize is undefined here: https://github.com/angular/angular.js/blob/g3_v1_3/src/ng/filter/filters.js#L152

undefined + 1 is NaN and NaN can't be bigger than number.

Fraction size is only computed if number has no exponent.

Is it by design?

[pkozlowski-opensource]

I believe this is a bug. I've sent #10252 with a potential fix.