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 (selectedItem != null && fComplianceLabels[i].equals(selectedItem)) {
					selectionIndex= i;
				}
				if (fInstalledJVMs[i] instanceof IVMInstall2) {
					fComplianceData[i]= JavaModelUtil.getCompilerCompliance((IVMInstall2) fInstalledJVMs[i], JavaCore.VERSION_1_4);
				} else {
					fComplianceData[i]= JavaCore.VERSION_1_4;
				}
			}
			comboField.setItems(fComplianceLabels);
			if (selectionIndex == -1) {
				fJRECombo.selectItem(getDefaultJVMName());
			} else {
				fJRECombo.selectItem(selectedItem);
			}
		}
		
		private IVMInstall[] getWorkspaceJREs() {
			List standins = new ArrayList();
			IVMInstallType[] types = JavaRuntime.getVMInstallTypes();
			for (int i = 0; i < types.length; i++) {
				IVMInstallType type = types[i];
				IVMInstall[] installs = type.getVMInstalls();
				for (int j = 0; j < installs.length; j++) {
					IVMInstall install = installs[j];
					standins.add(new VMStandin(install));
				}
			}
			return ((IVMInstall[])standins.toArray(new IVMInstall[standins.size()]));	
		}