Bug 323489 [KeyBindings] Reduce memory footprint of BindingManager
bundles/org.eclipse.jface/src/org/eclipse/jface/bindings/BindingManager.java
strokeCount += 2;
				}
				if ((modifierKeys & lookup.getShift()) != 0) {
					strokeCount += 4;
				}
				if ((modifierKeys & lookup.getCommand()) != 0) {
					strokeCount += 2;
				}
			} else {
				strokeCount += 99;
			}
		}
		return strokeCount;
	}
	/**
	 * <p>
	 * Creates a tree of context identifiers, representing the hierarchical
	 * structure of the given contexts. The tree is structured as a mapping from
	 * child to parent.
	 * </p>
	 * <p>
	 * This method completes in <code>O(n)</code>, where <code>n</code> is
	 * the height of the context tree.
	 * </p>
	 * 
	 * @param contextIds
	 *            The set of context identifiers to be converted into a tree;
	 *            must not be <code>null</code>.
	 * @return The tree of contexts to use; may be empty, but never
	 *         <code>null</code>. The keys and values are both strings.