Sniff wasn't dealing with abstract functions (ref #1650)

Author: gsherwood

src/Standards/Squiz/Sniffs/Commenting/FunctionCommentThrowTagSniff.php

@@ -42,6 +42,11 @@ public function process(File $phpcsFile, $stackPtr)
     {
         $tokens = $phpcsFile->getTokens();
 
+        if (isset($tokens[$stackPtr]['scope_closer']) === false) {
+            // Abstract or incomplete.
+            return;
+        }
+
         $find   = Tokens::$methodPrefixes;
         $find[] = T_WHITESPACE;
 

src/Standards/Squiz/Tests/Commenting/FunctionCommentThrowTagUnitTest.inc

@@ -403,3 +403,10 @@ class A
         }
     }
 }
+
+abstract class SomeClass {
+    /**
+     * Comment here.
+     */
+    abstract public function getGroups();
+}