Enable no-self-assign

This will throw an error on all variants of a = a;

http://eslint.org/docs/rules/no-self-assign

Change-Id: Iaddc5e106da307e9ead62d2a37876805aaa86746

.eslintrc

@@ -381,7 +381,7 @@ rules:
 
   # Disallow assignments where both sides are exactly the same
   # http://eslint.org/docs/rules/no-self-assign
-  no-self-assign: 0
+  no-self-assign: 2
 
   # Disallow comparisons where both sides are exactly the same
   # http://eslint.org/docs/rules/no-self-compare