Bug 123786 Following bug 109980, the compliance 6.0 should be added to the compiler's compliance list.
If the JRE/JDK used is a 1.6/6.0 VM, then the compliance 6.0 should be available. Compliance 1.6 implies source level 1.6 and target level 1.6.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/wizards/JavaProjectWizardFirstPage.java
if (fUseProjectJRE.isSelected()) {
				selectionIndex= comboField.getSelectionIndex();
				if (selectionIndex != -1) {
					selectedItem= comboField.getItems()[selectionIndex];
				}
			}
			
			fInstalledJVMs= getWorkspaceJREs();
			Arrays.sort(fInstalledJVMs, new Comparator() {
				public int compare(Object arg0, Object arg1) {
					IVMInstall i0= (IVMInstall)arg0;
					IVMInstall i1= (IVMInstall)arg1;
					if (i1 instanceof IVMInstall2 && i0 instanceof IVMInstall2) {
						String cc0= JavaModelUtil.getCompilerCompliance((IVMInstall2) i0, JavaCore.VERSION_1_4);
						String cc1= JavaModelUtil.getCompilerCompliance((IVMInstall2) i1, JavaCore.VERSION_1_4);
						int result= cc1.compareTo(cc0);
						if (result == 0)
							result= i0.getName().compareTo(i1.getName());
						return result;
					} else {
						return i0.getName().compareTo(i1.getName());
					}
				}
				
			});
			selectionIndex= -1;
			fComplianceLabels= new String[fInstalledJVMs.length];
			fComplianceData= new String[fInstalledJVMs.length];
			for (int i= 0; i < fInstalledJVMs.length; i++) {
				fComplianceLabels[i]= fInstalledJVMs[i].getName();