Limit global resolution to globalThis

Historically we've supported old platforms with a variety of fallback
options for determining a global object. However, our use of
Function('return this') is essentially an eval, which causes issues
for strict CSP.

On consulation with other teams, we think we can just rely on
globalThis at this point in time.

Author: dibenede

generator/js_generator.cc

@@ -3641,26 +3641,7 @@ void Generator::GenerateFile(const GeneratorOptions& options,
     if (options.import_style == GeneratorOptions::kImportCommonJsStrict) {
       printer->Print("var proto = {};\n\n");
     } else {
-      // To get the global object we call a function with .call(null), this will
-      // set "this" inside the function to the global object. This does not work
-      // if we are running in strict mode ("use strict"), so we fallback to the
-      // following things (in order from first to last):
-      // - globalThis: cross-platform standard, might not be defined in older
-      // versions of browsers
-      // - window: defined in browsers
-      // - global: defined in most server side environments like NodeJS
-      // - self: defined inside Web Workers (WorkerGlobalScope)
-      // - Function('return this')(): this will work on most platforms, but it
-      // may be blocked by things like CSP.
-      //   Function('') is almost the same as eval('')
-      printer->Print(
-          "var global =\n"
-          "    (typeof globalThis !== 'undefined' && globalThis) ||\n"
-          "    (typeof window !== 'undefined' && window) ||\n"
-          "    (typeof global !== 'undefined' && global) ||\n"
-          "    (typeof self !== 'undefined' && self) ||\n"
-          "    (function () { return this; }).call(null) ||\n"
-          "    Function('return this')();\n\n");
+      printer->Print("var global = globalThis;\n\n");
     }
 
     for (int i = 0; i < file->dependency_count(); i++) {

internal_options.js

@@ -28,14 +28,13 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 /**
- * @fileoverview Internal options for.
+ * @fileoverview Internal options.
  */
 goog.module('jspb.internal_options');
 
 /**
  * @return {boolean} True if BigInt is permitted for use and supported by the
  *     platform.
- * @nosideeffects
  */
 function isBigIntAvailable() {
   return goog.FEATURESET_YEAR >= 2021 || (typeof BigInt === 'function');