Allow simple modes to pass a mergeTokens option

FEATURE: Simple modes can now include a `mergeTokens` option in their language
data to disable token merging.

See https://discuss.codemirror.net/t/merging-adjacent-tokens-makes-completion-much-harder-when-it-merges-adjacent-bracket-tokens/9054/3

Author: marijnh

mode/simple-mode.d.ts

@@ -10,4 +10,5 @@ export interface Rule {
   dedent?: boolean | undefined;
   dedentIfLineStart?: boolean | undefined;
 }
-export declare function simpleMode<K extends string>(states: { [P in K]: P extends "languageData" ? {[name: string]: any} : Rule[] } & { start: Rule[] }): StreamParser<unknown>
+export declare function simpleMode<K extends string>(
+  states: { [P in K]: P extends "languageData" ? {[name: string]: any} : Rule[] } & { start: Rule[] }): StreamParser<unknown>

mode/simple-mode.js

@@ -22,6 +22,7 @@ export function simpleMode(states) {
     },
     token: tokenFunction(states_),
     indent: indentFunction(states_, meta),
+    mergeTokens: meta.mergeTokens,
     languageData: meta
   }
 };