the prototype given in the Object.create(SomeObject.prototype) should
really be a copy
Else overrrides on the sup object will change the original

Problem is that changing the supers prototype after the sub created a
copy is not seen anymore.

plugins/org.eclipse.dltk.javascript.core/src/org/eclipse/dltk/internal/javascript/ti/TypeInferencerVisitor.java

diff --git a/plugins/org.eclipse.dltk.javascript.core/src/org/eclipse/dltk/internal/javascript/ti/TypeInferencerVisitor.java b/plugins/org.eclipse.dltk.javascript.core/src/org/eclipse/dltk/internal/javascript/ti/TypeInferencerVisitor.java
index f31370e..d7a785e 100644
--- a/plugins/org.eclipse.dltk.javascript.core/src/org/eclipse/dltk/internal/javascript/ti/TypeInferencerVisitor.java
+++ b/plugins/org.eclipse.dltk.javascript.core/src/org/eclipse/dltk/internal/javascript/ti/TypeInferencerVisitor.java
@@ -596,7 +596,8 @@
 					&& RTypes.OBJECT.getDeclaration().equals(
 							method.getDeclaringType()) && arguments.length > 0) {
 				AnonymousValue value = new AnonymousValue();
-				value.addValue(arguments[0], false);
+				value.getValue().addValue(
+						((IValueProvider) arguments[0]).getValue());
 				if (arguments.length == 2) {
 					JSTypeSet types = arguments[1].getTypes();
 					for (IRType type : types) {