Bug 210496 Add hasStyle property in reportItemModel extension point
When chart gets reportItem's properties by extending ReportItem, style properties are null. Hence, model needs to add hasStyle property in reportItemModel extension point
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/metadata/ElementDefn.java
* implemented by the {@link ElementPropertyDefn}class. The few differences are
 * represented by the {@link SystemPropertyDefn}and
 * {@link org.eclipse.birt.report.model.api.core.UserPropertyDefn}classes.
 * 
 * <h3>Element Inheritance</h3>
 * 
 * Elements inherit from one another. There are two subtly different forms of
 * inheritance used in the system. First, the definition of element types uses
 * inheritance to simplify the description of the set of element types. For
 * example, the Data and Label elements are both types of the ReportItem
 * element.
 * <p>
 * Inheritance in the type system is described in this class (ElementDefn). Such
 * inheritance is constant for all designs. Type system inheritance, by
 * definition, allows one type of element to inherit from another.
 * <p>
 * Like any OO hierarchy, the element type system starts with certain abstract
 * base types such as ReportElement or ReportItem. While these are important for
 * describing the type system, they are irrelevant (or worse, confusing) to the
 * user. Thus, they are private to the implementation and not generally visible
 * to the user. (It is not a secret that they exist -- the XML design format is
 * open -- but it is not relevant to the business of building a report.) Such
 * elements are marked as abstract.
 * <p>
 * The second form of inheritance is defined by the user. A user can define a
 * Label, for example, that has many special attributes. The user can then
 * create other labels that derive from the first. User-defined inheritance is
 * subtly different from type-system inheritance. User cannot define new element
 * types; they can only set properties and customize existing types.
 * <p>