Fix performance regression in refactored syntax cache setup. More doc improvements. * syntax.h (enum syntax_source): New. Specify whether syntax is from property or buffer. (struct syntax_cache): Use enum syntax_source source, instead of no_syntax_table_prop and use_code. Improve comments. (SOURCE_IS_TABLE): New predicate. (SYNTAX_CODE_FROM_CACHE): Use it instead of use_code, and adjust logic. * syntax.c (syntax_cache_table_was_changed): Check cache->source (cache->no_syntax_table_prop is gone). (reset_syntax_cache_range): All information about OBJECT and BUFFER is in CACHE already. Also reset markers in OBJECT if it is a buffer. Rename INFINITE to VALID_EVERYWHERE. (init_syntax_cache): Initialize source (cache->no_syntax_table_prop is gone). Maybe initialize start and end to null markers. Initialize cache range with reset_syntax_cache_range. (update_syntax_cache): Use source instead of no_syntax_table_prop and use_code. (setup_syntax_cache): Add header comment. Improve other comments. Make calls to reset_syntax_cache_range and init_syntax_cache match their prototypes. (init_buffer_syntax_cache): Use init_syntax_cache to do the work. (signal_syntax_cache_extent_changed): Make call to reset_syntax_cache_range match its prototype. Improve local variable naming.