diff --git a/mozilla/content/html/content/src/nsImageMapUtils.cpp b/mozilla/content/html/content/src/nsImageMapUtils.cpp
index 4fdddfdc7ed..6aa6c1bcf7d 100644
--- a/mozilla/content/html/content/src/nsImageMapUtils.cpp
+++ b/mozilla/content/html/content/src/nsImageMapUtils.cpp
@@ -56,56 +56,44 @@ nsresult nsImageMapUtils::FindImageMap(nsIDocument *aDocument,
   NS_ENSURE_ARG_POINTER(aMap);
   *aMap = nsnull;
 
-  /* we used to strip the whitespace from the usemap value as a Quirk, but it was too quirky and
-     didn't really work correctly - see bug 87050 
-   */
+  // We used to strip the whitespace from the usemap value as a Quirk,
+  // but it was too quirky and didn't really work correctly - see bug
+  // 87050
 
   if (aUsemap.IsEmpty())
     return NS_OK;
 
-  PRInt32 hash = aUsemap.FindChar('#');
   nsAString::const_iterator start, end;
+  aUsemap.BeginReading(start);
+  aUsemap.EndReading(end);
+
+  PRInt32 hash = aUsemap.FindChar('#');
   if (hash > -1) {
-    aUsemap.BeginReading(start);
-    aUsemap.EndReading(end);
+    // aUsemap contains a '#', set start to point right after the '#'
     start.advance(hash + 1);
-    if (start == end)
+
+    if (start == end) {
       return NS_OK; // aUsemap == "#"
+    }
   }
 
-  // At this point, if hash < 0, then there was no '#'
-  // so aUsemap IS the ref. Otherwise the ref starts
-  // from 'start'
-
-  // NOTE!
-  // I'd really like to do this, but it won't compile, and casting
-  // Substring return to (const nsAString&) will cause a runtime crash.
-  // Therefore, to avoid doing needless work, this pattern is replicated
-  // below where we actually call functions with 'usemap' values.
-  //const nsAString &usemap = (hash < 0) ? aUsemap : Substring(start, end);
+  const nsAString& usemap(Substring(start, end));
 
   nsCOMPtr<nsIHTMLDocument> htmlDoc(do_QueryInterface(aDocument));
   if (htmlDoc) {
-    // See above NOTE
-    if (hash < 0) {
-      htmlDoc->GetImageMap(aUsemap, aMap);
-    } else {
-      htmlDoc->GetImageMap(Substring(start, end), aMap);
-    }
+    htmlDoc->GetImageMap(usemap, aMap);
   } else {
-    // XHTML requires that where a name attribute was used in HTML 4.01,
-    // the ID attribute must be used in XHTML. name is officially deprecated.
-    // This simplifies our life becase we can simply get the map with
+    // For XHTML elements embedded in non-XHTML documents we get the
+    // map by id since XHTML requires that where a "name" attribute
+    // was used in HTML 4.01, the "id" attribute must be used in
+    // XHTML. The attribute "name" is officially deprecated.  This
+    // simplifies our life becase we can simply get the map with
     // getElementById().
     nsCOMPtr<nsIDOMDocument> domDoc(do_QueryInterface(aDocument));
     if (domDoc) {
       nsCOMPtr<nsIDOMElement> element;
-      // See above NOTE
-      if (hash < 0) {
-        domDoc->GetElementById(aUsemap, getter_AddRefs(element));
-      } else {
-        domDoc->GetElementById(Substring(start, end), getter_AddRefs(element));
-      }
+      domDoc->GetElementById(usemap, getter_AddRefs(element));
+
       if (element) {
         CallQueryInterface(element, aMap);
       }
diff --git a/mozilla/content/html/document/src/nsHTMLDocument.cpp b/mozilla/content/html/document/src/nsHTMLDocument.cpp
index ddc56680e71..04f7db6956f 100644
--- a/mozilla/content/html/document/src/nsHTMLDocument.cpp
+++ b/mozilla/content/html/document/src/nsHTMLDocument.cpp
@@ -1138,29 +1138,38 @@ nsHTMLDocument::GetImageMap(const nsAString& aMapName,
     return NS_ERROR_NULL_POINTER;
   }
 
+  *aResult = nsnull;
+
   nsAutoString name;
   PRUint32 i, n = mImageMaps.Count();
 
   for (i = 0; i < n; i++) {
     nsCOMPtr<nsIDOMHTMLMapElement> map = mImageMaps[i];
-    if (map && NS_SUCCEEDED(map->GetName(name))) {
-      PRBool match;
+    NS_ASSERTION(map, "Null map in map list!");
 
-      if (IsXHTML()) {
-        match = name.Equals(aMapName);
-      } else {
-        match = name.Equals(aMapName, nsCaseInsensitiveStringComparator());
-      }
+    PRBool match;
+    nsresult rv;
 
-      if (match) {
-        *aResult = map;
-        NS_ADDREF(*aResult);
-        return NS_OK;
-      }
+    if (IsXHTML()) {
+      rv = map->GetId(name);
+
+      match = name.Equals(aMapName);
+    } else {
+      rv = map->GetName(name);
+
+      match = name.Equals(aMapName, nsCaseInsensitiveStringComparator());
+    }
+
+    NS_ENSURE_SUCCESS(rv, rv);
+
+    if (match) {
+      *aResult = map;
+      NS_ADDREF(*aResult);
+      return NS_OK;
     }
   }
 
-  return NS_ERROR_FAILURE;
+  return NS_OK;
 }
 
 NS_IMETHODIMP
diff --git a/mozilla/content/shared/src/nsImageMapUtils.cpp b/mozilla/content/shared/src/nsImageMapUtils.cpp
index 4fdddfdc7ed..6aa6c1bcf7d 100644
--- a/mozilla/content/shared/src/nsImageMapUtils.cpp
+++ b/mozilla/content/shared/src/nsImageMapUtils.cpp
@@ -56,56 +56,44 @@ nsresult nsImageMapUtils::FindImageMap(nsIDocument *aDocument,
   NS_ENSURE_ARG_POINTER(aMap);
   *aMap = nsnull;
 
-  /* we used to strip the whitespace from the usemap value as a Quirk, but it was too quirky and
-     didn't really work correctly - see bug 87050 
-   */
+  // We used to strip the whitespace from the usemap value as a Quirk,
+  // but it was too quirky and didn't really work correctly - see bug
+  // 87050
 
   if (aUsemap.IsEmpty())
     return NS_OK;
 
-  PRInt32 hash = aUsemap.FindChar('#');
   nsAString::const_iterator start, end;
+  aUsemap.BeginReading(start);
+  aUsemap.EndReading(end);
+
+  PRInt32 hash = aUsemap.FindChar('#');
   if (hash > -1) {
-    aUsemap.BeginReading(start);
-    aUsemap.EndReading(end);
+    // aUsemap contains a '#', set start to point right after the '#'
     start.advance(hash + 1);
-    if (start == end)
+
+    if (start == end) {
       return NS_OK; // aUsemap == "#"
+    }
   }
 
-  // At this point, if hash < 0, then there was no '#'
-  // so aUsemap IS the ref. Otherwise the ref starts
-  // from 'start'
-
-  // NOTE!
-  // I'd really like to do this, but it won't compile, and casting
-  // Substring return to (const nsAString&) will cause a runtime crash.
-  // Therefore, to avoid doing needless work, this pattern is replicated
-  // below where we actually call functions with 'usemap' values.
-  //const nsAString &usemap = (hash < 0) ? aUsemap : Substring(start, end);
+  const nsAString& usemap(Substring(start, end));
 
   nsCOMPtr<nsIHTMLDocument> htmlDoc(do_QueryInterface(aDocument));
   if (htmlDoc) {
-    // See above NOTE
-    if (hash < 0) {
-      htmlDoc->GetImageMap(aUsemap, aMap);
-    } else {
-      htmlDoc->GetImageMap(Substring(start, end), aMap);
-    }
+    htmlDoc->GetImageMap(usemap, aMap);
   } else {
-    // XHTML requires that where a name attribute was used in HTML 4.01,
-    // the ID attribute must be used in XHTML. name is officially deprecated.
-    // This simplifies our life becase we can simply get the map with
+    // For XHTML elements embedded in non-XHTML documents we get the
+    // map by id since XHTML requires that where a "name" attribute
+    // was used in HTML 4.01, the "id" attribute must be used in
+    // XHTML. The attribute "name" is officially deprecated.  This
+    // simplifies our life becase we can simply get the map with
     // getElementById().
     nsCOMPtr<nsIDOMDocument> domDoc(do_QueryInterface(aDocument));
     if (domDoc) {
       nsCOMPtr<nsIDOMElement> element;
-      // See above NOTE
-      if (hash < 0) {
-        domDoc->GetElementById(aUsemap, getter_AddRefs(element));
-      } else {
-        domDoc->GetElementById(Substring(start, end), getter_AddRefs(element));
-      }
+      domDoc->GetElementById(usemap, getter_AddRefs(element));
+
       if (element) {
         CallQueryInterface(element, aMap);
       }