build: remove unnecessary `internal-angular` karma reporter (#24803)

The reporter was added in 87d56acda, with the purpose of fixing
source-map paths (which was apparently needed back then). Things have
moved around a lot since then and the custom reporter doesn't seem to be
necessary any more. By removing the reporter, we have one less thing to
worry about while upgrading karma; plus we get improvements in built-in
reporters for free.

Output with the custom reporter:
```
at someMethod (packages/core/.../some-file.ts:13:37)
```

Output with the built-in reporter:
```
at someMethod (packages/core/.../some-file.ts:13.37 <- dist/all/@angular/core/.../some-file.js:1:337)
```

PR Close #24803

karma-js.conf.js

@@ -8,7 +8,6 @@
 
 const browserProvidersConf = require('./browser-providers.conf');
 const {generateSeed} = require('./tools/jasmine-seed-generator');
-const internalAngularReporter = require('./tools/karma/reporter');
 
 // Karma configuration
 // Generated on Thu Sep 25 2014 11:52:02 GMT-0700 (PDT)
@@ -96,7 +95,6 @@ module.exports = function(config) {
       'karma-sauce-launcher',
       'karma-chrome-launcher',
       'karma-sourcemap-loader',
-      internalAngularReporter,
     ],
 
     preprocessors: {
@@ -113,7 +111,7 @@ module.exports = function(config) {
       '/base/angular/': '/base/',
     },
 
-    reporters: ['internal-angular'],
+    reporters: ['dots'],
     sauceLabs: {
       testName: 'Angular2',
       retryLimit: 3,

scripts/ci/test-saucelabs.sh

@@ -10,5 +10,5 @@ source ${thisDir}/_travis-fold.sh
 travisFoldStart "test.unit.saucelabs"
   ./scripts/sauce/sauce_connect_block.sh
   SAUCE_ACCESS_KEY=`echo $SAUCE_ACCESS_KEY | rev`
-  $(npm bin)/karma start ./karma-js.conf.js --single-run --browsers=${KARMA_JS_BROWSERS} --reporters internal-angular,saucelabs
+  $(npm bin)/karma start ./karma-js.conf.js --single-run --browsers=${KARMA_JS_BROWSERS} --reporters dots,saucelabs
 travisFoldEnd "test.unit.saucelabs"

tools/karma/reporter.js

@@ -1,95 +0,0 @@
-/**
- * @license
- * Copyright Google Inc. All Rights Reserved.
- *
- * Use of this source code is governed by an MIT-style license that can be
- * found in the LICENSE file at https://angular.io/license
- */
-
-'use strict';
-
-const DotsColorReporter = require('karma/lib/reporters/dots_color');
-const {SourceMapConsumer} = require('source-map');
-const {resolve} = require('url');
-
-// Based on `karma/lib/reporter.js` (v2.0.4):
-// https://github.com/karma-runner/karma/blob/v2.0.4/lib/reporter.js
-function createErrorFormatter(config, emitter, SourceMapConsumer) {
-  const basePath = config.basePath;
-  const urlRoot = (config.urlRoot === '/') ? '' : (config.urlRoot || '');
-  const urlRegexp = new RegExp(
-      '(?:https?:\\/\\/' + config.hostname + '(?:\\:' + config.port + ')?' +
-          ')?\\/?' + urlRoot + '\\/?' +
-          '(base/|absolute)' +  // prefix, including slash for base/ to create relative paths.
-          '((?:[A-z]\\:)?[^\\?\\s\\:]*)' +  // path
-          '(\\?\\w*)?' +                    // sha
-          '(\\:(\\d+))?' +                  // line
-          '(\\:(\\d+))?' +                  // column
-          '',
-      'g');
-  const sourceMapConsumerCache = new WeakMap();
-  let lastServedFiles = [];
-
-  // Helpers
-  const findFile = path => lastServedFiles.find(f => f.path === path);
-  const formatPathMapping = (path, line, column) =>
-      path + (line ? `:${line}` : '') + (column ? `:${column}` : '');
-  const isString = input => typeof input === 'string';
-  const getSourceMapConsumer = sourceMap => {
-    if (!sourceMapConsumerCache.has(sourceMap)) {
-      sourceMapConsumerCache.set(sourceMap, new SourceMapConsumer(sourceMap));
-    }
-    return sourceMapConsumerCache.get(sourceMap);
-  };
-
-  emitter.on('file_list_modified', files => lastServedFiles = files.served);
-
-  return (input, indentation) => {
-    if (!isString(indentation)) indentation = '';
-    if (!input) input = '';
-    if (isString(input.message)) input = input.message;
-    if (!isString(input)) input = JSON.stringify(input, null, indentation);
-
-    let msg = input.replace(urlRegexp, (_, prefix, path, __, ___, line, ____, column) => {
-      const normalizedPath = (prefix === 'base/') ? `${basePath}/${path}` : path;
-      const file = findFile(normalizedPath);
-
-      if (file && file.sourceMap && line) {
-        line = +line;
-        column = +column || 0;
-        const bias =
-            column ? SourceMapConsumer.GREATEST_LOWER_BOUND : SourceMapConsumer.LEAST_UPPER_BOUND;
-
-        try {
-          const original =
-              getSourceMapConsumer(file.sourceMap).originalPositionFor({line, column, bias});
-          return formatPathMapping(
-              `${resolve(path, original.source)}`, original.line, original.column);
-        } catch (e) {
-          console.warn(`SourceMap position not found for trace: ${input}`);
-        }
-      }
-
-      return formatPathMapping(path, line, column) || prefix;
-    });
-
-    // Indent every line.
-    if (indentation) {
-      msg = indentation + msg.replace(/\n/g, `\n${indentation}`);
-    }
-
-    return config.formatError ? config.formatError(msg) : `${msg}\n`;
-  };
-}
-
-
-InternalAngularReporter.$inject = ['config', 'emitter'];
-function InternalAngularReporter(config, emitter) {
-  var formatter = createErrorFormatter(config, emitter, SourceMapConsumer);
-  DotsColorReporter.call(this, formatter, false, config.colors, config.browserConsoleLogOptions);
-}
-
-
-module.exports = {
-  'reporter:internal-angular': ['type', InternalAngularReporter],
-};