Rewrite tests.
Rewrite tests.

Also disable a test that was triggering a compiler bug in Visual
Studio 2012. The disabled tests were only sanity checks and weren't
testing the double-conversion library.

Conflicts:
	test/cctest/test-bignum-dtoa.cc
	test/cctest/test-fast-dtoa.cc
	test/cctest/test-strtod.cc

bos/double-conversion,bos/double-conversion,bos/double-conversion