Add testcase for GH-191 fix

tests/ecmascript/test-err-callstack-headroom.js

@@ -0,0 +1,47 @@
+/*
+ *  Error handling callstack headroom (GH-191)
+ *
+ *  When a RangeError is thrown due to the Ecmascript callstack limit being
+ *  reached, there should be enough headroom for at least 10 further recursions.
+ *  Prior to Duktape 1.3, this wasn't the case and a DoubleError would be
+ *  generated if the callstack limit was reached and, e.g. Duktape.errCreate
+ *  is set.
+ */
+
+/*---
+{
+    "custom": true
+}
+---*/
+
+/*===
+10
+9
+8
+7
+6
+5
+4
+3
+2
+1
+RangeError: callstack limit
+===*/
+
+try {
+	function recurse(n) {
+		print(n);
+		if (--n > 0) recurse(n);
+	}
+
+	Duktape.errCreate = function(e) {
+		recurse(10);
+		return e;
+	};
+
+	function f() { f(); }
+	f();
+}
+catch(e) {
+	print(e);
+}