[birt-dev]CheckIn: Fix Bugzilla Bug 157126 --- Confusion in IImageInstan

["Wei Zhao (Shang)" <wei.zhao@xxxxxxxxxxx>]

Title: [birt-dev]CheckIn: Fix Bugzilla Bug 157126 --- Confusion in IImageInstance.setImageSource()

- Summary:
Correct the javadoc of IImageInstance.getImageSource().

- Bugzilla Bug (s) Resolved:
Fix Bugzilla Bug 157126 --- Confusion in IImageInstance.getImageSource()

- Description:
The imageSource tpye should be using the description in IImageContent not ImageItemDesign.

- Tests Description  :
Manual Test.

- Notes to Build Team:

- Notes to Developers:

- Notes to QA:  
 
- Notes to Documentation:  

- Files Edited:
"/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/api/script/instance/IImageInstance.java"

- Files Added:

- Files Deleted

-Wei Zhao( Shanghai )