Let NullPtr.h define nullptr_t in C++11 mode with STLport.

I'm playing with -std=gnu++11 on Android, and this is the first thing that
fails to compile with this flag:

../../third_party/WebKit/Source/wtf/HashTraits.h:126:22:error: no type named 'nullptr_t' in namespace 'std'
        typedef std::nullptr_t EmptyValueType;
                ~~~~~^

(It's possible this won't go anywhere, in which case I'll revert this.)

BUG=none
R=abarth@chromium.org

Review URL: https://codereview.chromium.org/18238017

git-svn-id: svn://svn.chromium.org/blink/trunk@154080 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Introduce css3TextEnabled instead of CSS3_TEXT.

Introduce css3TextEnabled instead of CSS3_TEXT,
and remove '-webkit' prefix from the '-webkit-text-align-last' property.

BUG=259332

Review URL: https://chromiumcodereview.appspot.com/19041005

git-svn-id: svn://svn.chromium.org/blink/trunk@154081 bbb929c8-8fbe-4397-9dbb-9b2b20218538