diff --git a/mozilla/content/html/style/src/nsHTMLStyleSheet.cpp b/mozilla/content/html/style/src/nsHTMLStyleSheet.cpp
index 4e0c42ec5a1..d6e7b7ae57b 100644
--- a/mozilla/content/html/style/src/nsHTMLStyleSheet.cpp
+++ b/mozilla/content/html/style/src/nsHTMLStyleSheet.cpp
@@ -147,8 +147,13 @@ private:
 public:
   nsMapAttributesFunc mMapFunc;
   nsIHTMLAttributes*  mAttributes;
-  PRUint32            mHashSet: 1;
-  PRUint32            mHashCode: 31;
+  union {
+    struct {
+      PRUint32        mHashSet: 1;
+      PRUint32        mHashCode: 31;
+    };
+    PRUint32          mBitfiledInitializer; // this is a hack to allow initialization without pruify complaining about a UMR
+  };
 };
 
 AttributeKey::AttributeKey(nsMapAttributesFunc aMapFunc, nsIHTMLAttributes* aAttributes)
@@ -156,8 +161,7 @@ AttributeKey::AttributeKey(nsMapAttributesFunc aMapFunc, nsIHTMLAttributes* aAtt
     mAttributes(aAttributes)
 {
   NS_ADDREF(mAttributes);
-  mHashSet = 0;
-  mHashCode = 0;
+  mBitfiledInitializer = 0;
 }
 
 AttributeKey::~AttributeKey(void)
diff --git a/mozilla/layout/html/style/src/nsHTMLStyleSheet.cpp b/mozilla/layout/html/style/src/nsHTMLStyleSheet.cpp
index 4e0c42ec5a1..d6e7b7ae57b 100644
--- a/mozilla/layout/html/style/src/nsHTMLStyleSheet.cpp
+++ b/mozilla/layout/html/style/src/nsHTMLStyleSheet.cpp
@@ -147,8 +147,13 @@ private:
 public:
   nsMapAttributesFunc mMapFunc;
   nsIHTMLAttributes*  mAttributes;
-  PRUint32            mHashSet: 1;
-  PRUint32            mHashCode: 31;
+  union {
+    struct {
+      PRUint32        mHashSet: 1;
+      PRUint32        mHashCode: 31;
+    };
+    PRUint32          mBitfiledInitializer; // this is a hack to allow initialization without pruify complaining about a UMR
+  };
 };
 
 AttributeKey::AttributeKey(nsMapAttributesFunc aMapFunc, nsIHTMLAttributes* aAttributes)
@@ -156,8 +161,7 @@ AttributeKey::AttributeKey(nsMapAttributesFunc aMapFunc, nsIHTMLAttributes* aAtt
     mAttributes(aAttributes)
 {
   NS_ADDREF(mAttributes);
-  mHashSet = 0;
-  mHashCode = 0;
+  mBitfiledInitializer = 0;
 }
 
 AttributeKey::~AttributeKey(void)
diff --git a/mozilla/layout/style/nsHTMLStyleSheet.cpp b/mozilla/layout/style/nsHTMLStyleSheet.cpp
index 4e0c42ec5a1..d6e7b7ae57b 100644
--- a/mozilla/layout/style/nsHTMLStyleSheet.cpp
+++ b/mozilla/layout/style/nsHTMLStyleSheet.cpp
@@ -147,8 +147,13 @@ private:
 public:
   nsMapAttributesFunc mMapFunc;
   nsIHTMLAttributes*  mAttributes;
-  PRUint32            mHashSet: 1;
-  PRUint32            mHashCode: 31;
+  union {
+    struct {
+      PRUint32        mHashSet: 1;
+      PRUint32        mHashCode: 31;
+    };
+    PRUint32          mBitfiledInitializer; // this is a hack to allow initialization without pruify complaining about a UMR
+  };
 };
 
 AttributeKey::AttributeKey(nsMapAttributesFunc aMapFunc, nsIHTMLAttributes* aAttributes)
@@ -156,8 +161,7 @@ AttributeKey::AttributeKey(nsMapAttributesFunc aMapFunc, nsIHTMLAttributes* aAtt
     mAttributes(aAttributes)
 {
   NS_ADDREF(mAttributes);
-  mHashSet = 0;
-  mHashCode = 0;
+  mBitfiledInitializer = 0;
 }
 
 AttributeKey::~AttributeKey(void)