Fix test failure for 32 bit official build.

Official 32 bit builds seem to generate x86 fpu instructions while normal
development settings and Chromium settings generate SSE instructions. GCC has a
loss of precision bug (gcc.gnu.org/PR323) that results in a different floating
point value in some cases. This bug can be worked around by storing the
intermediate value in a variable.

BUG=334475

Review URL: https://codereview.chromium.org/135643006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@245343 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 245343