'when' should use intrinsics for '=='

#KT-19029 Fixed Target versions 1.1.5
 #KT-18818 Fixed Target versions 1.1.5

compiler/testData/codegen/bytecodeText/when/whenNull.kt

@@ -0,0 +1,10 @@
+fun test(a: Any?, b: Any?, c: Any?) {
+    when (null) {
+        a -> throw IllegalArgumentException("a is null")
+        b -> throw IllegalArgumentException("b is null")
+        c -> throw IllegalArgumentException("c is null")
+    }
+}
+
+// 0 areEqual
+// 3 IFNONNULL