Simplify findWasmBinary() and reduce usage of isDataURI(). NFC (#23549)

The `findWasmBinary()` function only exists when SINGLE_FILE is not
true.

Also, the only time `WASM_BINARY_FILE` can be a data URL is in
SINGLE_FILE mode.

Author: sbc100

src/base64Decode.js

@@ -60,6 +60,14 @@ function base64Decode(b64) {
 #endif // ~WASM2JS
 
 #if !MINIMAL_RUNTIME
+// Prefix of data URIs emitted by SINGLE_FILE and related options.
+var dataURIPrefix = 'data:application/octet-stream;base64,';
+
+/**
+ * Indicates whether filename is a base64 data URI.
+ */
+var isDataURI = (uri) => uri.startsWith(dataURIPrefix);
+
 // If filename is a base64 data URI, parses and returns data (Buffer on node,
 // Uint8Array otherwise). If filename is not a base64 data URI, returns undefined.
 function tryParseAsDataURI(filename) {

src/preamble.js

@@ -140,15 +140,6 @@ var runtimeInitialized = false;
 var runtimeExited = false;
 #endif
 
-// Prefix of data URIs emitted by SINGLE_FILE and related options.
-var dataURIPrefix = 'data:application/octet-stream;base64,';
-
-/**
- * Indicates whether filename is a base64 data URI.
- * @noinline
- */
-var isDataURI = (filename) => filename.startsWith(dataURIPrefix);
-
 /**
  * Indicates whether filename is delivered via file protocol (as opposed to http/https)
  * @noinline
@@ -606,18 +597,13 @@ function findWasmBinary() {
 #if EXPORT_ES6 && USE_ES6_IMPORT_META && !AUDIO_WORKLET
   if (Module['locateFile']) {
 #endif
-    var f = '{{{ WASM_BINARY_FILE }}}';
-#if !SINGLE_FILE
-    if (!isDataURI(f)) {
-      return locateFile(f);
-    }
-#endif
-    return f;
-#if EXPORT_ES6 && USE_ES6_IMPORT_META && !AUDIO_WORKLET // In single-file mode, repeating WASM_BINARY_FILE would emit the contents again. For an Audio Worklet, we cannot use `new URL()`.
+    return locateFile('{{{ WASM_BINARY_FILE }}}');
+#if EXPORT_ES6 && USE_ES6_IMPORT_META && !AUDIO_WORKLET // For an Audio Worklet, we cannot use `new URL()`.
   }
 #if ENVIRONMENT_MAY_BE_SHELL
-  if (ENVIRONMENT_IS_SHELL)
+  if (ENVIRONMENT_IS_SHELL) {
     return '{{{ WASM_BINARY_FILE }}}';
+  }
 #endif
   // Use bundler-friendly `new URL(..., import.meta.url)` pattern; works in browsers too.
   return new URL('{{{ WASM_BINARY_FILE }}}', import.meta.url).href;
@@ -800,9 +786,7 @@ async function instantiateArrayBuffer(binaryFile, imports) {
 
 async function instantiateAsync(binary, binaryFile, imports) {
 #if !SINGLE_FILE
-  if (!binary &&
-      typeof WebAssembly.instantiateStreaming == 'function' &&
-      !isDataURI(binaryFile)
+  if (!binary && typeof WebAssembly.instantiateStreaming == 'function'
 #if ENVIRONMENT_MAY_BE_WEBVIEW
       // Don't use streaming for file:// delivered objects in a webview, fetch them synchronously.
       && !isFileURI(binaryFile)

src/source_map_support.js

@@ -97,9 +97,7 @@ WasmSourceMap.prototype.normalizeOffset = function (offset) {
 }
 
 var wasmSourceMapFile = '{{{ WASM_BINARY_FILE }}}.map';
-if (!isDataURI(wasmSourceMapFile)) {
-  wasmSourceMapFile = locateFile(wasmSourceMapFile);
-}
+wasmSourceMapFile = locateFile(wasmSourceMapFile);
 
 function getSourceMap() {
   var buf = readBinary(wasmSourceMapFile);

test/browser/test_small_js_flags.js.size

@@ -1 +1 @@
-4343
+4248

test/other/codesize/test_codesize_cxx_ctors1.gzsize

@@ -1 +1 @@
-8357
+8308

test/other/codesize/test_codesize_cxx_ctors1.jssize

@@ -1 +1 @@
-20268
+20171

test/other/codesize/test_codesize_cxx_ctors2.gzsize

@@ -1 +1 @@
-8341
+8291

test/other/codesize/test_codesize_cxx_ctors2.jssize

@@ -1 +1 @@
-20247
+20150

test/other/codesize/test_codesize_cxx_except.gzsize

@@ -1 +1 @@
-9363
+9309

test/other/codesize/test_codesize_cxx_except.jssize

@@ -1 +1 @@
-24036
+23939