While the EcmaScript specification doesn't define precise values for the
Math constants or the Math functions, we should at least ensure that the
values of the constants and the functions agree, i.e. Math.E should be
exactly the same value as Math.exp(1).

Also make sure that Math.exp(1) returns the expected value; we should
revisit the fdlibm algorithm and figure out why it's wrong in the last
bit.

CQ_INCLUDE_TRYBOTS=tryserver.chromium.linux:linux_chromium_rel_ng;tryserver.blink:linux_blink_rel
BUG=chromium:626111,v8:3266,v8:3468,v8:3493,v8:5086,v8:5108
R=yangguo@chromium.org

Review-Url: https://codereview.chromium.org/2079233005
Cr-Commit-Position: refs/heads/master@{#37128}