fix isDataURI, it must be used in the HTML as well as JS (#5963)

Author: kripken

emcc.py

@@ -2609,8 +2609,8 @@ def generate_html(target, options, js_target, target_basename,
 
   # when script.inline isn't empty, add required helper functions such as tryParseAsDataURI
   if script.inline:
-    for file in ['src/arrayUtils.js', 'src/base64Utils.js']:
-      f = open(shared.path_from_root(file), 'r')
+    for file in ['arrayUtils.js', 'base64Utils.js', 'URIUtils.js']:
+      f = open(shared.path_from_root('src', file), 'r')
       script.inline = f.read() + script.inline
       f.close()
 

src/URIUtils.js

@@ -0,0 +1,10 @@
+// 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.
+function isDataURI(filename) {
+  return String.prototype.startsWith ?
+      filename.startsWith(dataURIPrefix) :
+      filename.indexOf(dataURIPrefix) === 0;
+}
+

src/preamble.js

@@ -1987,16 +1987,7 @@ Module['FS_createPreloadedFile'] = FS.createPreloadedFile;
 var cyberDWARFFile = '{{{ BUNDLED_CD_DEBUG_FILE }}}';
 #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.
-function isDataURI(filename) {
-  return String.prototype.startsWith ?
-      filename.startsWith(dataURIPrefix) :
-      filename.indexOf(dataURIPrefix) === 0
-  ;
-}
+#include "URIUtils.js"
 
 #if BINARYEN
 function integrateWasmJS() {