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/preferences/ComplianceConfigurationBlock.java
composite.setLayout(layout);
		
		fControlsComposite= new Composite(composite, SWT.NONE);
		fControlsComposite.setFont(composite.getFont());
		
		layout= new GridLayout();
		layout.marginHeight= 0;
		layout.marginWidth= 0;
		layout.numColumns= 1;
		fControlsComposite.setLayout(layout);
		int nColumns= 3;
		layout= new GridLayout();
		layout.numColumns= nColumns;
		Group group= new Group(fControlsComposite, SWT.NONE);
		group.setFont(fControlsComposite.getFont());
		group.setText(PreferencesMessages.ComplianceConfigurationBlock_compliance_group_label); 
		group.setLayoutData(new GridData(GridData.FILL, GridData.FILL, false, false));
		group.setLayout(layout);
	
		String label= PreferencesMessages.ComplianceConfigurationBlock_compiler_compliance_label; 
		addComboBox(group, label, PREF_COMPLIANCE, values345, values345Labels, 0);
		label= PreferencesMessages.ComplianceConfigurationBlock_default_settings_label; 
		addCheckBox(group, label, INTR_DEFAULT_COMPLIANCE, new String[] { DEFAULT_CONF, USER_CONF }, 0);	
		int indent= fPixelConverter.convertWidthInCharsToPixels(2);
		Control[] otherChildren= group.getChildren();	
				
		String[] versions= new String[] { VERSION_1_1, VERSION_1_2, VERSION_1_3, VERSION_1_4, VERSION_1_5 };
		String[] versionsLabels= new String[] {
			PreferencesMessages.ComplianceConfigurationBlock_version11,  
			PreferencesMessages.ComplianceConfigurationBlock_version12,