Fix some build breaks.

tools/dom/templates/html/dartium/html_dartium.darttemplate

Index: tools/dom/templates/html/dartium/html_dartium.darttemplate
diff --git a/tools/dom/templates/html/dartium/html_dartium.darttemplate b/tools/dom/templates/html/dartium/html_dartium.darttemplate
index 4bd7279dea509a1dab4397a3a9d88d2121f87e69..7d6572c5d0275b1e731f580c5d5d84cca25a9180 100644
--- a/tools/dom/templates/html/dartium/html_dartium.darttemplate
+++ b/tools/dom/templates/html/dartium/html_dartium.darttemplate
@@ -415,12 +415,17 @@ wrap_jso(jsObject) {
     }
 
     var constructor = js.JsNative.getProperty(jsObject, 'constructor');
-    if (__interop_checks) {
-      debug_or_assert("constructor != null", constructor != null);
+    if (constructor == null) {
+      // Perfectly valid case for JavaScript objects where __proto__ has
+      // intentionally been set to null.
+      js.setDartHtmlWrapperFor(jsObject, jsObject);
+      return jsObject;
     }
     var jsTypeName = js.JsNative.getProperty(constructor, 'name');
-    if (__interop_checks) {
-      debug_or_assert("constructor != null && jsTypeName.length > 0", constructor != null && jsTypeName.length > 0);
+    if (jsTypeName is! String || jsTypeName.length == 0) {
+      // Not an html type.
+      js.setDartHtmlWrapperFor(jsObject, jsObject);
+      return jsObject;
     }
 
     var dartClass_instance;
@@ -490,12 +495,17 @@ wrap_jso_no_SerializedScriptvalue(jsObject) {
     }
 
     var constructor = js.JsNative.getProperty(jsObject, 'constructor');
-    if (__interop_checks) {
-      debug_or_assert("constructor != null", constructor != null);
+    if (constructor == null) {
+      // Perfectly valid case for JavaScript objects where __proto__ has
+      // intentionally been set to null.
+      js.setDartHtmlWrapperFor(jsObject, jsObject);
+      return jsObject;
     }
     var jsTypeName = js.JsNative.getProperty(constructor, 'name');
-    if (__interop_checks) {
-      debug_or_assert("constructor != null && jsTypeName.length > 0", constructor != null && jsTypeName.length > 0);
+    if (jsTypeName is! String || jsTypeName.length == 0) {
+      // Not an html type.
+      js.setDartHtmlWrapperFor(jsObject, jsObject);
+      return jsObject;
     }
 
     var func = getHtmlCreateFunction(jsTypeName);