Port d5f2ac5e

Original commit message:

    Import base::ieee754::exp() from FreeBSD msun and introduce a Float64Exp
    TurboFan operator based on that, similar to what we do for Float64Log.
    Rewrite Math.exp() as TurboFan builtin and use that operator to also
    inline Math.exp() into optimized TurboFan functions.

R=bmeurer@chromium.org, mvstanton@chromium.org, joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com, mbrandy@us.ibm.com

BUG=v8:3266,v8:3468,v8:3493,v8:5086,v8:5108,chromium:620786
LOG=N

Review-Url: https://codereview.chromium.org/2075263002
Cr-Commit-Position: refs/heads/master@{#37073}