Run this to generate a list of tests that are skipped on e10s. Adjust objdir and srcdir accordingly.

find-e10s-tests.js

"use strict";
const path = require("path");
const fs = require('fs');

const objdir = "/Users/felipe/moz/mozilla-central/ff-opt/";
const srcdir = "/Users/felipe/moz/mozilla-central/mozilla/";

const flavor = process.argv[2] || "browser-chrome";

console.log("Disabled " + flavor + " tests:\n");

/* skipped
  mochitest-plain:
    dom/browser-element/mochitest/mochitest-oop.ini
    dom/canvas/test/_webgl-conformance.ini
    dom/browser-element/mochitest/mochitest.ini
*/

/* 
  possible flavors (and their total counts as of 2015-12-15 are:
  reftest: 19220
  web-platform-tests: 5973
  crashtest: 2934
  browser-chrome: 3014
  mochitest: 6384
  xpcshell: 2816
  chrome: 1270
  a11y: 288
  jetpack-addon: 40
  jetpack-package: 142
  webapprt-chrome: 16
  webapprt-content: 2
*/

let allTests = JSON.parse(fs.readFileSync(objdir + "all-tests.json", "utf-8"));
let manifests = {};

for (let name in allTests) {
  let test = allTests[name];

  for (let entry of test) {
    if (entry.flavor == flavor) {
      handleTest(entry);
    }
  }
}

showResults();
displayStats();

// ================== //

function handleTest(test) {
  if (test.subsuite == "devtools") {
    return;
  }

  let manifestName = path.relative(srcdir, test.manifest);

  if (manifestName == "dom/browser-element/mochitest/mochitest-oop.ini" ||
      manifestName == "dom/canvas/test/_webgl-conformance.ini" ||
      manifestName == "dom/browser-element/mochitest/mochitest.ini") {
    return;
  }

  let manifest;
  if (!manifests[manifestName]) {
    manifest = manifests[manifestName] = {
      disabled: [],
      enabled: []
    };
  } else {
    manifest = manifests[manifestName];
  }

  let skipIf = test["skip-if"] || "";
  let disabledForE10s = skipIf.includes("e10s") &&
                        !skipIf.includes("!e10s");

  manifest[disabledForE10s ? "disabled" : "enabled"].push(test);
}

function spc(count) {
  if (count < 1) count = 1;
  let ret = "";
  while (count--) {
    ret += " ";
  }
  return ret;
}

function showResults() {
  for (let manifestName in manifests) {
    let manifest = manifests[manifestName];

    if (manifest.disabled.length == 0) {
      continue;
    }

    console.log(manifestName + ":");

    let largestName = 0;
    for (let test of manifest.disabled) {
      let testLength = test.name.length;
      if (test.tags) {
        testLength += test.tags.length + 3;
      }
      largestName = Math.max(largestName, testLength);
    }

    for (let test of manifest.disabled) {
      let name = test.name;
      if (test.tags) {
        name += " (" + test.tags + ")";
      }

      console.log("  " + name + spc(largestName + 4 - name.length) + "skip-if = " + test["skip-if"].substr(0,100) + (test["skip-if"].length > 100 ? "..." : ""));
    }

    console.log("");
  }
}

function displayStats() {
  let enabled = 0, disabled = 0;
  for (let manifestName in manifests) {
    let manifest = manifests[manifestName];
    enabled += manifest.enabled.length;
    disabled += manifest.disabled.length;
  }

  let total = enabled + disabled;

  function pct(a, b) {
    return (Math.round((a/b) * 10000) / 100);
  }

  console.log("Total tests:    " + total);
  console.log("Enabled tests:  " + enabled + " (" + pct(enabled, total) + "%)");
  console.log("Disabled tests: " + disabled + " (" + pct(disabled, total) + "%)");
}