Avoid Scanner::peek reading beyond end of data

Masterminds\HTML5\Parser\Scanner::peek() reads beyond the end of
actual data, which leads to a "Uninitialized string offset" warning.

Fixes: #215

Author: ohader

src/HTML5/Parser/Scanner.php

@@ -104,7 +104,7 @@ public function position()
      */
     public function peek()
     {
-        if (($this->char + 1) <= $this->EOF) {
+        if (($this->char + 1) < $this->EOF) {
             return $this->data[$this->char + 1];
         }
 

test/HTML5/Parser/TokenizerTest.php

@@ -213,6 +213,7 @@ public function testComment()
             '<!--Hello' => 'Hello',
             "<!--\0Hello" => UTF8Utils::FFFD . 'Hello',
             '<!--' => '',
+            '<!--<!--' => '<!--',
         );
         foreach ($fail as $test => $expected) {
             $events = $this->parse($test);