diff --git a/src/components/script/dom/bindings/codegen/CodegenRust.py b/src/components/script/dom/bindings/codegen/CodegenRust.py
index 8d89fe1b879..c1e9f488222 100644
--- a/src/components/script/dom/bindings/codegen/CodegenRust.py
+++ b/src/components/script/dom/bindings/codegen/CodegenRust.py
@@ -9,7 +9,7 @@ import string
 import operator
 
 from WebIDL import *
-from Configuration import NoSuchDescriptorError, Descriptor
+from Configuration import Descriptor
 
 AUTOGENERATED_WARNING_COMMENT = \
     "/* THIS FILE IS AUTOGENERATED - DO NOT EDIT */\n\n"
@@ -498,9 +498,6 @@ def getJSToNativeConversionTemplate(type, descriptorProvider, failureCode=None,
     # they really should be!
     if exceptionCode is None:
         exceptionCode = "return 0;"
-    # We often want exceptionCode to be indented, since it often appears in an
-    # if body.
-    exceptionCodeIndented = CGIndenter(CGGeneric(exceptionCode))
 
     # Unfortunately, .capitalize() on a string will lowercase things inside the
     # string, which we do not want.
@@ -620,12 +617,6 @@ def getJSToNativeConversionTemplate(type, descriptorProvider, failureCode=None,
                                           failureCode)
             return (template, declType, None, isOptional, None)
 
-        # Sequences and callbacks have to hold a strong ref to the thing being
-        # passed down.
-        forceOwningType = descriptor.interface.isCallback() or isMember
-
-        typePtr = descriptor.nativeType
-
         templateBody = ""
         if descriptor.interface.isConsequential():
             raise TypeError("Consequential interface %s being used as an "
@@ -648,7 +639,7 @@ def getJSToNativeConversionTemplate(type, descriptorProvider, failureCode=None,
         templateBody = wrapObjectTemplate(templateBody, isDefinitelyObject,
                                           type, failureCode)
 
-        declType = CGGeneric(typePtr)
+        declType = CGGeneric(descriptor.nativeType)
         if type.nullable() or isOptional:
             declType = CGWrapper(declType, pre="Option<", post=">")
 
@@ -812,15 +803,9 @@ def getJSToNativeConversionTemplate(type, descriptorProvider, failureCode=None,
         assert not isOptional
 
         typeName = CGDictionary.makeDictionaryName(type.inner)
-        actualTypeName = typeName
         selfRef = "${declName}"
 
-        declType = CGGeneric(actualTypeName)
-
-        # If we're a member of something else, the const
-        # will come from the Optional or our container.
-        if not isMember:
-            selfRef = "%s" % selfRef
+        declType = CGGeneric(typeName)
 
         # We do manual default value handling here, because we
         # actually do want a jsval, and we only handle null anyway
@@ -833,7 +818,7 @@ def getJSToNativeConversionTemplate(type, descriptorProvider, failureCode=None,
         template = ("%s = %s::new();\n"
                     "if %s.Init(cx, %s) == 0 {\n"
                     "  return 0;\n"
-                    "}" % (selfRef, actualTypeName, selfRef, val))
+                    "}" % (selfRef, typeName, selfRef, val))
 
         return (template, declType, None, False, None)
 
@@ -846,11 +831,7 @@ def getJSToNativeConversionTemplate(type, descriptorProvider, failureCode=None,
     if not type.isPrimitive():
         raise TypeError("Need conversion for argument type '%s'" % str(type))
 
-    conversionBehavior = "eDefault"
-    if isEnforceRange:
-        conversionBehavior = "eEnforceRange"
-    elif isClamp:
-        conversionBehavior = "eClamp"
+    assert not isEnforceRange and not isClamp
 
     if failureCode is None:
         failureCode = 'return 0'
@@ -934,8 +915,6 @@ def instantiateJSToNativeConversionTemplate(templateTuple, replacements,
 
     originalDeclName = replacements["declName"]
     if declType is not None:
-        if dealWithOptional:
-            mutableDeclType = CGWrapper(declType, pre="Option< ", post=" >")
         newDecl = [CGGeneric("let mut "),
                    CGGeneric(originalDeclName),
                    CGGeneric(": "),
@@ -2246,7 +2225,6 @@ class CGCallGenerator(CGThing):
                 name = "(JSObject&)" + name
             #XXXjdm Perhaps we should pass all nontrivial types by borrowed pointer
             if a.type.isGeckoInterface():
-                argDescriptor = descriptorProvider.getDescriptor(a.type.name)
                 if not (a.type.nullable() or a.optional):
                     name = "&mut " + name
             elif a.type.isDictionary():
@@ -2906,15 +2884,12 @@ def getUnionTypeTemplateVars(type, descriptorProvider):
         name = type.name
         typeName = "/*" + type.name + "*/"
 
-    (template, declType, holderType,
+    (template, _, holderType,
      dealWithOptional, initialValue) = getJSToNativeConversionTemplate(
         type, descriptorProvider, failureCode="return Ok(None);",
         exceptionCode='return Err(());',
         isDefinitelyObject=True, isOptional=False)
 
-    structType = declType.define()
-    externalType = getUnionAccessorSignatureType(type, descriptorProvider).define()
-
     assert not type.isObject()
     jsConversion = string.Template(template).substitute({
         "val": "value",
@@ -3546,7 +3521,6 @@ class CGProxySpecialOperation(CGPerSignatureCall):
         operation = descriptor.operations[operation]
         assert len(operation.signatures()) == 1
         signature = operation.signatures()[0]
-        extendedAttributes = descriptor.getExtendedAttributes(operation)
 
         (returnType, arguments) = signature
 
@@ -4050,13 +4024,16 @@ class CGDescriptor(CGThing):
                         else:
                             hasSetter = True
                     cgThings.append(CGMemberJITInfo(descriptor, m))
-            if hasMethod: cgThings.append(CGGenericMethod(descriptor))
-            if hasGetter: cgThings.append(CGGenericGetter(descriptor))
-            #if hasLenientGetter: cgThings.append(CGGenericGetter(descriptor,
-            #                                                     lenientThis=True))
-            if hasSetter: cgThings.append(CGGenericSetter(descriptor))
-            #if hasLenientSetter: cgThings.append(CGGenericSetter(descriptor,
-            #                                                     lenientThis=True))
+            if hasMethod:
+                cgThings.append(CGGenericMethod(descriptor))
+            if hasGetter:
+                cgThings.append(CGGenericGetter(descriptor))
+            if hasLenientGetter:
+                pass
+            if hasSetter:
+                cgThings.append(CGGenericSetter(descriptor))
+            if hasLenientSetter:
+                pass
 
         if descriptor.concrete:
             cgThings.append(CGClassFinalizeHook(descriptor))
diff --git a/src/components/script/dom/webidls/Blob.webidl b/src/components/script/dom/webidls/Blob.webidl
index 9e7bec50c0a..8fd13ea32fa 100644
--- a/src/components/script/dom/webidls/Blob.webidl
+++ b/src/components/script/dom/webidls/Blob.webidl
@@ -16,8 +16,8 @@ interface Blob {
   readonly attribute unsigned long long size;
   readonly attribute DOMString type;
 
-  Blob slice([Clamp] optional long long start,
-             [Clamp] optional long long end,
+  Blob slice(/*[Clamp]*/ optional long long start,
+             /*[Clamp]*/ optional long long end,
              optional DOMString contentType);
   void close();
 };