Revert 271905 "Roll pdfium to get fixes for build warnings."

> Roll pdfium to get fixes for build warnings.
> 
> a3f590b  Add Matt Giuca to AUTHORS.
> 4db62f5  Fixed or silenced all warnings and turned on warnings-as-errors.
> 2c4b046  cf2hints: Fix early loop termination causing hints to be ignored.
> 4fbe779  Add some blank lines at the end of 3 files to remove the "no newlines at end of file" warning.
> 6f9095f  Add my @chromium account in the AUTHORS file.
> 54c1825  Remove "using namespace agg" to make it clear which code is using agg, and also so we can turn compiler warnings into errors.
> 5ce98f5  Fix warning on Mac.
> 41f0590  Remove "using namespace v8" in header. This allows us to turn all warnings into errors. It also makes it clearer to find usage of v8 in the library.
> 
> R=thestig@chromium.org
> 
> Review URL: https://codereview.chromium.org/295983005

TBR=jam@chromium.org

Review URL: https://codereview.chromium.org/296913002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@271907 0039d316-1c4b-4281-b951-d872f2087c98

DEPS

@@ -77,7 +77,7 @@ vars = {
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling PDFIum
   # and whatever else without interference from each other.
-  "pdfium_revision": "a3f590b60af4bf50c00df4cf9565cc6df0b5667c",
+  "pdfium_revision": "951f241bcf22f0095abe2f109adfdd9c19e76d70",
 }
 
 deps = {