[wasm64] Fix glSharedSource in >4gb mode and enable test under wasm64

Author: sbc100

.circleci/config.yml

@@ -816,6 +816,7 @@ jobs:
             browser64_4gb.test_async_*
             browser64_4gb.test_audio_worklet*
             browser64_4gb.test_emscripten_log
+            browser64_4gb.test_clientside_vertex_arrays_es3
             "
   test-browser-firefox:
     executor: bionic

src/library_webgl.js

@@ -425,8 +425,8 @@ for (/**@suppress{duplicate}*/var i = 0; i < {{{ GL_POOL_TEMP_BUFFERS_SIZE }}};
     getSource: (shader, count, string, length) => {
       var source = '';
       for (var i = 0; i < count; ++i) {
-        var len = length ? {{{ makeGetValue('length', 'i*4', 'i32') }}} : -1;
-        source += UTF8ToString({{{ makeGetValue('string', 'i*4', 'i32') }}}, len < 0 ? undefined : len);
+        var len = length ? {{{ makeGetValue('length', 'i*' * POINTER_SIZE, '*') }}} : -1;
+        source += UTF8ToString({{{ makeGetValue('string', 'i*' + POINTER_SIZE, '*') }}}, len < 0 ? undefined : len);
       }
 #if LEGACY_GL_EMULATION
       // Let's see if we need to enable the standard derivatives extension