Add script to remove prefixed CSS from third_party/polymer.

third_party/polymer/v1_0/css_strip_prefixes.js

+/**
+ * @fileoverview Script to remove CSS prefixed rules that don't apply to
+ * Chromium.
+ */
+var fs = require('fs');
+var glob = require('glob').sync;
+var path = require('path');
+/**
+ * Strips CSS rules/attributes from the file in-place.
+ * @param {string} filename The filename to process.
+ */
+function processFile(filename) {
+  var fileContents = fs.readFileSync(filename, {'encoding': 'utf-8'});
+  var lines = fileContents.split('\n');
+  var processedFileContents = reconstructFile(lines, findLinesToRemove(lines));
+  fs.writeFileSync(filename, processedFileContents);
+  console.log('processedFile', filename);
+}
+/**
+ * @return {!Array<string>} lines
+ * @return {!Array<number>} The lines numbers that need to be removed in
+ *     ascinding order.
+ */
+function findLinesToRemove(lines) {
+  // Regex used to detect CSS attributes or even entire CSS rules to be removed.
+  var prefixRegex = new RegExp(/-webkit-|-moz-|-ms-/);
+  // Regexes used to remove entire CSS rules that can span multiple lines.
+  var cssRulesToRemove = [
+    new RegExp(/@-webkit-keyframes/),
+    new RegExp(/-moz-placeholder/),
+    new RegExp(/-ms-input-placeholder/),
+  ];
+  // Regexes used to preserve a CSS rule that can span multiple lines.
+  var cssRulesToPreserve = [
+    new RegExp(/-webkit-appearance/),
+    new RegExp(/-webkit-font-smoothing/),
+    new RegExp(/-webkit-overflow-scrolling/),
+    new RegExp(/-webkit-tap-highlight/),
+  ];
+  var openingBracketRegex = new RegExp(/{/);
+  var closingBracketRegex = new RegExp(/}/);
+  // Whether currently visited line is within a CSS rule that should be removed.
+  var inCssRuleToRemove = false;
+  // Whether currently visited line is within a CSS rule that should be
+  // preserved.
+  var inCssRuleToPreserve = false;
+  // Current number of nested-levels with respect to curly braces.
+  var levelCounter = 0;
+  return lines.reduce(function(soFar, line, index) {
+    if (inCssRuleToRemove || inCssRuleToPreserve) {
+      if (openingBracketRegex.test(line)) {
+        levelCounter++;
+      }
+      if (closingBracketRegex.test(line)) {
+        levelCounter--;
+      }
+      if (!inCssRuleToPreserve) {
+        soFar.push(index);
+      }
+      if (levelCounter == 0) {
+        inCssRuleToRemove = false;
+        inCssRuleToPreserve = false;
+      }
+    } else if (prefixRegex.test(line)) {
+      inCssRuleToRemove = cssRulesToRemove.some(
+          function(regex) { return regex.test(line); });
+      inCssRuleToPreserve = cssRulesToPreserve.some(
+          function(regex) { return regex.test(line); });
+      if (inCssRuleToRemove || inCssRuleToPreserve) {
+        levelCounter++;
+        if (inCssRuleToRemove) {
+          soFar.push(index);
+        }
+      } else {
+        soFar.push(index);
+      }
+    }
+    return soFar;
+  }, []);
+}
+/**
+ * Generates the final processed file.
+ * @param {!Array<string>} lines The lines to be process.
+ * @param {!Array<number>} linesToRemove Indices of the lines to be removed in
+ *     ascending order.
+ * @return {string} The contents of the processed file.
+ */
+function reconstructFile(lines, linesToRemove) {
+  var matchWhiteSpaceRegex = /\s+/;
+  // Process line numbers in descinding order, such that the array can be
+  // modified in-place.
+  linesToRemove.reverse().forEach(function(lineIndex) {
+    lines.splice(lineIndex, 1);
+  });
+  return lines.join('\n');
+}
+var srcDir = path.resolve(path.join(__dirname, 'components-chromium'));
+var htmlFiles = glob(srcDir + '/**/*.html');
+var cssFiles = glob(srcDir + '/**/*.css');
+htmlFiles.concat(cssFiles).forEach(processFile);
+console.log('DONE');