render lint squigglies 4x faster

* turns out codemirror lint addon doesn't open an overall op,
  instead it creates an op for each marker.

* also, now there's no need to disable the lint option when initializing codemirror

edit/edit.js

@@ -411,7 +411,6 @@ function setupCodeMirror(sectionDiv, code, index) {
     $('.code-label', sectionDiv).insertAdjacentElement('afterend', wrapper);
   }, {
     value: code,
-    lint: null,
   });
   const wrapper = cm.display.wrapper;
 

edit/lint-codemirror-helper.js

@@ -1,26 +1,43 @@
 /* global CodeMirror linterConfig */
 'use strict';
 
-CodeMirror.registerHelper('lint', 'csslint', code =>
-  linterConfig.invokeWorker({code, config: linterConfig.getCurrent()}).then(results =>
-    results.map(({line, col: ch, message, rule, type: severity}) => line && {
-      message,
-      from: {line: line - 1, ch: ch - 1},
-      to: {line: line - 1, ch},
-      rule: rule.id,
-      severity,
-    }).filter(Boolean)));
+(() => {
+  CodeMirror.registerHelper('lint', 'csslint', invokeHelper);
+  CodeMirror.registerHelper('lint', 'stylelint', invokeHelper);
 
-CodeMirror.registerHelper('lint', 'stylelint', code =>
-  linterConfig.invokeWorker({code, config: linterConfig.getCurrent()}).then(({results}) =>
-    !results[0] && [] ||
-    results[0].warnings.map(({line, column:ch, text, severity}) => ({
-      from: {line: line - 1, ch: ch - 1},
-      to: {line: line - 1, ch},
-      message: text
-        .replace('Unexpected ', '')
-        .replace(/^./, firstLetter => firstLetter.toUpperCase())
-        .replace(/\s*\([^(]+\)$/, ''), // strip the rule,
-      rule: text.replace(/^.*?\s*\(([^(]+)\)$/, '$1'),
-      severity,
-    }))));
+  const cookResults = {
+    csslint: results =>
+      results.map(({line, col: ch, message, rule, type: severity}) => line && {
+        message,
+        from: {line: line - 1, ch: ch - 1},
+        to: {line: line - 1, ch},
+        rule: rule.id,
+        severity,
+      }).filter(Boolean),
+
+    stylelint: ({results}) =>
+      !results[0] && [] ||
+      results[0].warnings.map(({line, column: ch, text, severity}) => ({
+        from: {line: line - 1, ch: ch - 1},
+        to: {line: line - 1, ch},
+        message: text
+          .replace('Unexpected ', '')
+          .replace(/^./, firstLetter => firstLetter.toUpperCase())
+          .replace(/\s*\([^(]+\)$/, ''), // strip the rule,
+        rule: text.replace(/^.*?\s*\(([^(]+)\)$/, '$1'),
+        severity,
+      })),
+  };
+
+  function invokeHelper(code, options, cm) {
+    const config = linterConfig.getCurrent();
+    return linterConfig.invokeWorker({code, config})
+      .then(cookResults[linterConfig.getName()])
+      .then(results => {
+        if (options && typeof options.preUpdateLinting === 'function') {
+          options.preUpdateLinting(cm);
+        }
+        return results;
+      });
+  }
+})();

edit/lint.js

@@ -44,7 +44,11 @@ var linterConfig = {
     return CodeMirror.lint && CodeMirror.lint[linter] ? {
       getAnnotations: CodeMirror.lint[linter],
       delay: prefs.get('editor.lintDelay'),
+      preUpdateLinting(cm) {
+        cm.startOperation();
+      },
       onUpdateLinting(annotationsNotSorted, annotations, cm) {
+        cm.endOperation();
         updateLintReport(cm, 0);
       },
     } : false;
@@ -198,7 +202,9 @@ function updateLinter({immediately, linter = linterConfig.getName()} = {}) {
     CodeMirror.defaults.lint = linterConfig.getForCodeMirror(linter);
     const guttersOption = prepareGuttersOption();
     editors.forEach(cm => {
-      cm.setOption('lint', CodeMirror.defaults.lint);
+      if (cm.options.lint !== CodeMirror.defaults.lint) {
+        cm.setOption('lint', CodeMirror.defaults.lint);
+      }
       if (guttersOption) {
         cm.setOption('guttersOption', guttersOption);
         updateGutters(cm, guttersOption);
@@ -235,14 +241,6 @@ function updateLinter({immediately, linter = linterConfig.getName()} = {}) {
 }
 
 function updateLintReport(cm, delay) {
-  if (cm && !cm.options.lint) {
-    // add 'lint' option back to the freshly created section
-    setTimeout(() => {
-      if (!cm.options.lint) {
-        cm.setOption('lint', linterConfig.getForCodeMirror());
-      }
-    });
-  }
   const state = cm && cm.state && cm.state.lint || {};
   if (delay === 0) {
     // immediately show pending csslint/stylelint messages in onbeforeunload and save