Use normal class declarations in libembind_shared.js. NFC

src/lib/libembind_shared.js

@@ -3,8 +3,18 @@
 // University of Illinois/NCSA Open Source License.  Both these licenses can be
 // found in the LICENSE file.
 var LibraryEmbindShared = {
-  $InternalError: "= class InternalError extends Error { constructor(message) { super(message); this.name = 'InternalError'; }}",
-  $BindingError: "= class BindingError extends Error { constructor(message) { super(message); this.name = 'BindingError'; }}",
+  $InternalError: class extends Error {
+    constructor(message) {
+      super(message);
+      this.name = 'InternalError';
+    }
+  },
+  $BindingError: class extends Error {
+    constructor(message) {
+      super(message);
+      this.name = 'BindingError';
+    }
+  },
 
   $throwInternalError__deps: ['$InternalError'],
   $throwInternalError: (message) => { throw new InternalError(message); },

test/codesize/test_minimal_runtime_code_size_hello_embind.json

@@ -1,10 +1,10 @@
 {
   "a.html": 548,
   "a.html.gz": 371,
-  "a.js": 7249,
-  "a.js.gz": 3325,
+  "a.js": 7255,
+  "a.js.gz": 3331,
   "a.wasm": 7099,
   "a.wasm.gz": 3246,
-  "total": 14896,
-  "total_gz": 6942
+  "total": 14902,
+  "total_gz": 6948
 }

test/codesize/test_minimal_runtime_code_size_hello_embind_val.json

@@ -1,10 +1,10 @@
 {
   "a.html": 548,
   "a.html.gz": 371,
-  "a.js": 5346,
-  "a.js.gz": 2515,
+  "a.js": 5349,
+  "a.js.gz": 2514,
   "a.wasm": 5741,
   "a.wasm.gz": 2690,
-  "total": 11635,
-  "total_gz": 5576
+  "total": 11638,
+  "total_gz": 5575
 }