PPAPI: Make ASSERT macros print values of operands

With this patch, if one of our ASSERT macros fails, the error
string will contain the expected and actual values.

I made a browser test for it. I would prefer a
unit test, but I didn't want to have to mix test_case.h with
our unit tests.

BUG=None

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=246129

Review URL: https://codereview.chromium.org/123463007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@246757 0039d316-1c4b-4281-b951-d872f2087c98
Update trace file format for NaN/Infinit values to use strings

Turns out my previous fix was inadequate - the trace viewer doesn't expect
null values for arguments.  Instead just use hard-coded strings (better
anyway since it's clearer to the user what happened).

BUG=336787

Review URL: https://codereview.chromium.org/135573004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@246758 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 246758