Update globals for chrome 53.0.2785.46.

Change-Id: I67f8827baf6aa7198c9474ffa9eff8538b9961fe
diff --git a/dev/core/src/com/google/gwt/dev/js/globals/chrome.txt b/dev/core/src/com/google/gwt/dev/js/globals/chrome.txt
index 7d693ae..df795b9 100644
--- a/dev/core/src/com/google/gwt/dev/js/globals/chrome.txt
+++ b/dev/core/src/com/google/gwt/dev/js/globals/chrome.txt
@@ -184,6 +184,7 @@
 HTMLQuoteElement
 HTMLScriptElement
 HTMLSelectElement
+HTMLSlotElement
 HTMLShadowElement
 HTMLSourceElement
 HTMLSpanElement