diff --git a/dom/bindings/parser/WebIDL.py b/dom/bindings/parser/WebIDL.py
index f568aad64287..085129f277f7 100644
--- a/dom/bindings/parser/WebIDL.py
+++ b/dom/bindings/parser/WebIDL.py
@@ -1330,7 +1330,7 @@ class IDLInterfaceOrNamespace(IDLObjectWithScope, IDLExposureMixins):
                 if not indexedGetter:
                     raise WebIDLError("Interface with value iterator does not "
                                       "support indexed properties",
-                                      [self.location, iterableDecl.location])
+                                      [self.location])
 
                 if iterableDecl.valueType != indexedGetter.signatures()[0][0]:
                     raise WebIDLError("Iterable type does not match indexed "
@@ -1341,7 +1341,7 @@ class IDLInterfaceOrNamespace(IDLObjectWithScope, IDLExposureMixins):
                 if not hasLengthAttribute:
                     raise WebIDLError('Interface with value iterator does not '
                                       'have an integer-typed "length" attribute',
-                                      [self.location, iterableDecl.location])
+                                      [self.location])
             else:
                 assert iterableDecl.isPairIterator()
                 if indexedGetter:
@@ -1350,11 +1350,6 @@ class IDLInterfaceOrNamespace(IDLObjectWithScope, IDLExposureMixins):
                                       [self.location, iterableDecl.location,
                                        indexedGetter.location])
 
-        if indexedGetter and not hasLengthAttribute:
-            raise WebIDLError('Interface with an indexed getter does not have '
-                              'an integer-typed "length" attribute',
-                              [self.location, indexedGetter.location])
-
     def isExternal(self):
         return False
 
diff --git a/dom/bindings/test/TestCodeGen.webidl b/dom/bindings/test/TestCodeGen.webidl
index ded1c097c308..1511a6e55fba 100644
--- a/dom/bindings/test/TestCodeGen.webidl
+++ b/dom/bindings/test/TestCodeGen.webidl
@@ -1180,7 +1180,6 @@ interface TestIndexedGetterAndSetterAndNamedGetterInterface {
   getter DOMString (DOMString myName);
   getter long (unsigned long index);
   setter creator void (unsigned long index, long arg);
-  readonly attribute unsigned long length;
 };
 
 interface TestIndexedAndNamedGetterInterface {
@@ -1192,7 +1191,6 @@ interface TestIndexedAndNamedGetterInterface {
 interface TestIndexedSetterInterface {
   setter creator void setItem(unsigned long idx, DOMString item);
   getter DOMString (unsigned long idx);
-  readonly attribute unsigned long length;
 };
 
 interface TestNamedSetterInterface {
@@ -1203,7 +1201,6 @@ interface TestNamedSetterInterface {
 interface TestIndexedAndNamedSetterInterface {
   setter creator void (unsigned long index, TestIndexedSetterInterface item);
   getter TestIndexedSetterInterface (unsigned long index);
-  readonly attribute unsigned long length;
   setter creator void setNamedItem(DOMString name, TestIndexedSetterInterface item);
   getter TestIndexedSetterInterface (DOMString name);
 };
diff --git a/dom/bindings/test/TestExampleGen.webidl b/dom/bindings/test/TestExampleGen.webidl
index 2ebbb16d5fe9..03a39f2007d6 100644
--- a/dom/bindings/test/TestExampleGen.webidl
+++ b/dom/bindings/test/TestExampleGen.webidl
@@ -434,7 +434,6 @@ interface TestExampleInterface {
   void passUnion((object or long) arg);
   // Some union tests are debug-only to avoid creating all those
   // unused union types in opt builds.
-
 #ifdef DEBUG
   void passUnion2((long or boolean) arg);
   void passUnion3((object or long or boolean) arg);
@@ -804,7 +803,6 @@ interface TestExampleInterface {
 interface TestExampleProxyInterface {
   getter long longIndexedGetter(unsigned long ix);
   setter creator void longIndexedSetter(unsigned long y, long z);
-  readonly attribute unsigned long length;
   stringifier DOMString myStringifier();
   getter short shortNameGetter(DOMString nom);
   deleter void (DOMString nomnom);
diff --git a/dom/webidl/OfflineResourceList.webidl b/dom/webidl/OfflineResourceList.webidl
index abdf562c73ce..abc5118881dd 100644
--- a/dom/webidl/OfflineResourceList.webidl
+++ b/dom/webidl/OfflineResourceList.webidl
@@ -93,12 +93,6 @@ partial interface OfflineResourceList {
   [Throws]
   getter DOMString mozItem(unsigned long index);
 
-  /**
-   * We need a "length" to actually be valid Web IDL, given that we have an
-   * indexed getter.
-   */
-  readonly attribute unsigned long length;
-
   /**
    * Add an item to the list of dynamically-managed entries.  The resource
    * will be fetched into the application cache.