Bug 554687 patch 2: Use nsSMILValue::Swap instead of operator= where appropriate. r=roc

content/smil/nsSMILAnimationFunction.cpp

@@ -301,7 +301,9 @@ nsSMILAnimationFunction::ComposeResult(const nsISMILAttr& aSMILAttr,
 
   // If additive animation isn't required or isn't supported, set the value.
   if (!IsAdditive() || NS_FAILED(aResult.SandwichAdd(result))) {
-    aResult = result;
+    aResult.Swap(result);
+    // Note: The old value of aResult is now in |result|, and it will get
+    // cleaned up when |result| goes out of scope, when this function returns.
   }
 }
 

content/svg/content/src/nsSVGAngle.cpp

@@ -453,7 +453,7 @@ nsSVGAngle::SMILOrient::ValueFromString(const nsAString& aStr,
     val.mU.mOrient.mUnit = unitType;
     val.mU.mOrient.mOrientType = nsIDOMSVGMarkerElement::SVG_MARKER_ORIENT_ANGLE;
   }
-  aValue = val;
+  aValue.Swap(val);
   aCanCache = PR_TRUE;
 
   return NS_OK;

content/svg/content/src/nsSVGTransformSMILAttr.cpp

@@ -186,8 +186,8 @@ nsSVGTransformSMILAttr::ParseValue(const nsAString& aSpec,
     return;
   }
 
-  // Success! Initialize our outparam with parsed value.
-  aResult = val;
+  // Success! Populate our outparam with parsed value.
+  aResult.Swap(val);
 }
 
 inline PRBool

content/svg/content/src/nsSVGViewBox.cpp

@@ -284,12 +284,8 @@ nsSVGViewBox::SMILViewBox
     return res;
   }
   nsSMILValue val(&SVGViewBoxSMILType::sSingleton);
-  // Check for OOM when the nsSMILValue ctor called SVGViewBoxSMILType::Init:
-  if (val.IsNull()) {
-    return NS_ERROR_OUT_OF_MEMORY;
-  }
   *static_cast<nsSVGViewBoxRect*>(val.mU.mPtr) = viewBox;
-  aValue = val;
+  aValue.Swap(val);
   aCanCache = PR_TRUE;
   
   return NS_OK;
@@ -299,10 +295,7 @@ nsSMILValue
 nsSVGViewBox::SMILViewBox::GetBaseValue() const
 {
   nsSMILValue val(&SVGViewBoxSMILType::sSingleton);
-  // Check for OOM when the nsSMILValue ctor called SVGViewBoxSMILType::Init:
-  if (!val.IsNull()) {
-    *static_cast<nsSVGViewBoxRect*>(val.mU.mPtr) = mVal->mBaseVal;
-  }
+  *static_cast<nsSVGViewBoxRect*>(val.mU.mPtr) = mVal->mBaseVal;
   return val;
 }