Port 7ceed92a
Port 89d8c57b

Original commit message:

    Import base::ieee754::atan() and base::ieee754::atan2() from fdlibm and
    introduce Float64Atan and Float64Atan2 TurboFan operators based on those,
    similar to what we already did for Float64Log and Float64Log1p. Rewrite
    Math.atan() and Math.atan2() as TurboFan builtin and use the operators
    to also inline Math.atan() and Math.atan2() into optimized TurboFan functions.

    Import base::ieee754::log1p() from fdlibm and introduce a Float64Log1p
    TurboFan operator based on that, similar to what we do for Float64Log.
    Rewrite Math.log1p() as TurboFan builtin and use that operator to also
    inline Math.log1p() into optimized TurboFan functions.

    Also unify the handling of the special IEEE 754 functions somewhat in
    the TurboFan backends. At some point we can hopefully express this
    completely in the InstructionSelector (once we have an idea what to do
    with the ST(0) return issue on IA-32/X87).

    Drive-by-fix: Add some more test coverage for the log function.

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

BUG=v8:5086,v8:5092,v8:5095
LOG=N

Review-Url: https://codereview.chromium.org/2061753002
Cr-Commit-Position: refs/heads/master@{#36935}