Always use a static message formats

These are the only places that seems to be including environment specific
variables in the message format.

By ensuring that they're static, we make it easier to group logs by
format. I also ensure that I keep each addendum separate so that they can
be filtered/grouped separately.

src/classic/element/ReactElementValidator.js

@@ -146,7 +146,7 @@ function warnAndMonitorForKeyUse(message, element, parentType) {
   }
   memoizer[useName] = true;
 
-  message +=
+  var parentOrOwnerAddendum =
     ownerName ? ` Check the render method of ${ownerName}.` :
     parentName ? ` Check the React.render call using <${parentName}>.` :
     '';
@@ -154,17 +154,22 @@ function warnAndMonitorForKeyUse(message, element, parentType) {
   // Usually the current owner is the offender, but if it accepts children as a
   // property, it may be the creator of the child that's responsible for
   // assigning it a key.
+  var childOwnerAddendum = '';
   if (element &&
       element._owner &&
       element._owner !== ReactCurrentOwner.current) {
     // Name of the component that originally created this child.
     var childOwnerName = getName(element._owner);
 
-    message += ` It was passed a child from ${childOwnerName}.`;
+    childOwnerAddendum = ` It was passed a child from ${childOwnerName}.`;
   }
 
-  message += ' See http://fb.me/react-warning-keys for more information.';
-  warning(false, message);
+  warning(
+    false,
+    message + '%s%s See http://fb.me/react-warning-keys for more information.',
+    parentOrOwnerAddendum,
+    childOwnerAddendum
+  );
 }
 
 /**
@@ -248,7 +253,7 @@ function checkPropTypes(componentName, propTypes, props, location) {
         loggedTypeFailures[error.message] = true;
 
         var addendum = getDeclarationErrorAddendum(this);
-        warning(false, 'Failed propType: ' + error.message + addendum);
+        warning(false, 'Failed propType: %s%s', error.message, addendum);
       }
     }
   }

src/core/ReactCompositeComponent.js

@@ -449,14 +449,16 @@ var ReactCompositeComponentMixin = {
             // Preface gives us something to blacklist in warning module
             warning(
               false,
-              'Failed Composite propType: %s',
-              error.message + addendum
+              'Failed Composite propType: %s%s',
+              error.message,
+              addendum
             );
           } else {
             warning(
               false,
-              'Failed Context Types: %s',
-              error.message + addendum
+              'Failed Context Types: %s%s',
+              error.message,
+              addendum
             );
           }
         }