Remove import.meta.url usage

import.meta.url is only at stage 3 of the standards and tools like webpack
and babel do not have good support. Not all browser do either.  I ran into
problems just trying to update the cesium-webpack-example because of it
and Edge won't even part JS code with import.meta.url in it.

This PR removes import.meta.url usage and just does a little extra work
so that all of our developer setups properly set CESIUM_BASE_URL. Most ES6
development setups would require setting CESIUM_BASE_URL anyway, so this
doesn't change much of anything for our end users.

Folks using combined versions of Cesium.js are unaffected.

I also tightened up our regex for `getBaseUrlFromCesiumScript` because
Cesium.js is always named Cesium.js if it is available, which wasn't the
case years ago when this code was written.  This should prevent accidental
detection of the wrong script, for example `CesiumViewer.js` would get
selected as a false positive.  This type of check is only valid for
non-ES6 module usage anyway, since there is no `script` tag inserter for
individual ES6 modules.

Fixes #8251 You can now load Cesium Viewer unbuilt in Edge (but it takes
forever)

Author: mramato

Apps/CesiumViewer/CesiumViewer.js

@@ -1,3 +1,5 @@
+window.CESIUM_BASE_URL = '../../Source/';
+
 import {
     Cartesian3,
     createWorldTerrain,

Apps/Sandcastle/load-cesium-es6.js

@@ -1,5 +1,6 @@
 // This file loads the unbuilt ES6 version of Cesium
 // into the global scope during local developmnet
+window.CESIUM_BASE_URL = "../../../Source/";
 import * as Cesium from "../../Source/Cesium.js";
 window.Cesium = Cesium;
 

Source/Core/buildModuleUrl.js

@@ -1,12 +1,11 @@
 import defined from './defined.js';
 import DeveloperError from './DeveloperError.js';
-import FeatureDetection from './FeatureDetection.js';
 import getAbsoluteUri from './getAbsoluteUri.js';
 import Resource from './Resource.js';
 
     /*global CESIUM_BASE_URL*/
 
-    var cesiumScriptRegex = /((?:.*\/)|^)cesium[\w-]*\.js(?:\W|$)/i;
+    var cesiumScriptRegex = /((?:.*\/)|^)Cesium\.js$/;
     function getBaseUrlFromCesiumScript() {
         var scripts = document.getElementsByTagName('script');
         for ( var i = 0, len = scripts.length; i < len; ++i) {
@@ -47,16 +46,10 @@ import Resource from './Resource.js';
             baseUrlString = CESIUM_BASE_URL;
         } else if (typeof define === 'object' && defined(define.amd) && !define.amd.toUrlUndefined && defined(require.toUrl)) {
             baseUrlString = getAbsoluteUri('..', buildModuleUrl('Core/buildModuleUrl.js'));
-        } else if (!FeatureDetection.isInternetExplorer() && /\/buildModuleUrl\.js$/.test(import.meta.url)) {
-            baseUrlString = getAbsoluteUri('..', import.meta.url);
         } else {
             baseUrlString = getBaseUrlFromCesiumScript();
         }
 
-        if (baseUrlString === '') {
-            baseUrlString = '.';
-        }
-
         //>>includeStart('debug', pragmas.debug);
         if (!defined(baseUrlString)) {
             throw new DeveloperError('Unable to determine Cesium base URL automatically, try defining a global variable called CESIUM_BASE_URL.');

Specs/Core/buildModuleUrlSpec.js

@@ -18,7 +18,6 @@ describe('Core/buildModuleUrl', function() {
         var r = buildModuleUrl._cesiumScriptRegex;
 
         expect(r.exec('Cesium.js')[1]).toEqual('');
-        expect(r.exec('assets/foo/Cesium-b16.js')[1]).toEqual('assets/foo/');
         expect(r.exec('assets/foo/Cesium.js')[1]).toEqual('assets/foo/');
         expect(r.exec('http://example.invalid/Cesium/assets/foo/Cesium.js')[1]).toEqual('http://example.invalid/Cesium/assets/foo/');
 

Specs/SpecRunner.html

@@ -27,6 +27,7 @@
             document.write('<script src="../Build/Specs/spec-main.js"><\/script>');
             document.write('<script src="../Build/Specs/Specs.js"><\/script>');
         } else {
+            window.CESIUM_BASE_URL = '../Source/';
             document.write('<script type="module" src="spec-main.js"><\/script>');
         }
     </script>

Specs/karma-main.js

@@ -15,5 +15,11 @@ if (__karma__.config.args) {
     release = __karma__.config.args[4];
 }
 
+if (release) {
+    window.CESIUM_BASE_URL = 'base/Build/Cesium';
+} else {
+    window.CESIUM_BASE_URL = 'base/Source';
+}
+
 jasmine.DEFAULT_TIMEOUT_INTERVAL = 30000;
 customizeJasmine(jasmine.getEnv(), included, excluded, webglValidation, webglStub, release);

gulpfile.js

@@ -1394,6 +1394,7 @@ function buildCesiumViewer() {
         var stream = mergeStream(
             gulp.src('Build/Apps/CesiumViewer/CesiumViewer.js')
                 .pipe(gulpInsert.prepend(copyrightHeader))
+                .pipe(gulpReplace('../../Source', '.'))
                 .pipe(gulp.dest(cesiumViewerOutputDirectory)),
 
             gulp.src('Apps/CesiumViewer/CesiumViewer.css')