Improve breakpoint generator of the debugger. (#1652)

Now the debugger generates a breakpoint for each function before
its first executable statement. This allows inspecting the function
arguments. Position (line and column) info is also added which
simplifies finding of anonymus functions. Several tests were
update to check more corner cases.

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

tests/debugger/do_step.js

@@ -14,12 +14,19 @@
 
 function f1()
 {
-  var i = 1;
+  function g()
+  {
+    return 6;
+  }
+
+  var i = g();
+  g();
 }
 
 function f2()
 {
-  var y = 2;
+  f1();
+  return 7;
 }
 
 f1();