Remove embind's extendError. NFC (#23987)

These days we can just write `extends Error`.

Author: sbc100

src/lib/libembind.js

@@ -28,10 +28,8 @@
 #include "libembind_shared.js"
 
 var LibraryEmbind = {
-  $UnboundTypeError__deps: ['$extendError'],
-  $UnboundTypeError: "=Module['UnboundTypeError'] = extendError(Error, 'UnboundTypeError')",
-  $PureVirtualError__deps: ['$extendError'],
-  $PureVirtualError: "=Module['PureVirtualError'] = extendError(Error, 'PureVirtualError')",
+  $UnboundTypeError: class extends Error {},
+  $PureVirtualError: class extends Error {},
   $GenericWireTypeSize: {{{ 2 * POINTER_SIZE }}},
 #if EMBIND_AOT
   $InvokerFunctions: '<<< EMBIND_AOT_OUTPUT >>>',
@@ -148,32 +146,6 @@ var LibraryEmbind = {
     }
   },
 
-  // from https://github.com/imvu/imvujs/blob/master/src/error.js
-  $extendError__deps: ['$createNamedFunction'],
-  $extendError: (baseErrorType, errorName) => {
-    var errorClass = createNamedFunction(errorName, function(message) {
-      this.name = errorName;
-      this.message = message;
-
-      var stack = (new Error(message)).stack;
-      if (stack !== undefined) {
-        this.stack = this.toString() + '\n' +
-            stack.replace(/^Error(:[^\n]*)?\n/, '');
-      }
-    });
-    errorClass.prototype = Object.create(baseErrorType.prototype);
-    errorClass.prototype.constructor = errorClass;
-    errorClass.prototype.toString = function() {
-      if (this.message === undefined) {
-        return this.name;
-      } else {
-        return `${this.name}: ${this.message}`;
-      }
-    };
-
-    return errorClass;
-  },
-
   $createNamedFunction: (name, func) => Object.defineProperty(func, 'name', { value: name }),
 
   $embindRepr: (v) => {

test/code_size/embind_hello_wasm.json

@@ -1,10 +1,10 @@
 {
   "a.html": 552,
   "a.html.gz": 380,
-  "a.js": 9475,
-  "a.js.gz": 4154,
+  "a.js": 9094,
+  "a.js.gz": 3993,
   "a.wasm": 7348,
   "a.wasm.gz": 3378,
-  "total": 17375,
-  "total_gz": 7912
+  "total": 16994,
+  "total_gz": 7751
 }

test/test_other.py

@@ -3363,7 +3363,7 @@ def test_embind(self, *extra_args):
       '-Wno-deprecated-declarations',
       '-lembind',
       '-sRETAIN_COMPILER_SETTINGS',
-      '-sEXPORTED_RUNTIME_METHODS=getCompilerSetting,setDelayFunction,flushPendingDeletes',
+      '-sEXPORTED_RUNTIME_METHODS=getCompilerSetting,setDelayFunction,flushPendingDeletes,PureVirtualError',
       '-sWASM_ASYNC_COMPILATION=0',
       # This test uses a `CustomSmartPtr` class which has 1MB of data embedded in
       # it which means we need more stack space than normal.