process method
Run the analyzer on every file that is a style sheet or any component that has a style tag.
Implementation
void process(StyleSheet styleSheet, {List<StyleSheet>? includes}) {
if (includes != null) {
processVarDefinitions(includes);
}
processVars(styleSheet);
// Remove all var definitions for this style sheet.
_RemoveVarDefinitions().visitTree(styleSheet);
}