Text Scanning Performance and Flexibility

In the original Squeak, text scanning and displaying are done by primitives if possible. The character to glyph mapping for a given size is one-to-one, so the program simply can lay the glyphs out from left to right. In the other words, text scanning doesn't need much flexibility.

However, for scanning other scripts, we need more flexibility to cope with the different layout rules in different scripts. We thought that some performance help from a new primitive would be necessary, but it turned out that an all Squeak solution was feasible.