HasInstance should accept the prototype of all functions. Fixes #1519. (#1520)

The regression-test-issue-736.js is also changed, since it expects
throwing an error, which does not happen anymore because the "x"
variable is undefined.

JerryScript-DCO-1.0-Signed-off-by: Zoltan Herczeg zherczeg.u-szeged@partner.samsung.com

tests/jerry/regression-test-issue-736.js

@@ -31,7 +31,7 @@ try {
 }
 
 try {
-  eval("var x; x instanceof assert;");
+  eval("var x = {}; x instanceof assert;");
   assert(false);
 } catch(e) {
   assert(e instanceof TypeError);