Added DontMergeClass test and fix docs

core/util/src/test/scala/net/liftweb/util/CssSelectorSpec.scala

@@ -503,7 +503,26 @@ object CssBindHelpersSpec extends Specification with XmlMatchers {
       (res \ "@class").length must_== 0
     }
 
+    "don't merge class attribute" in {
+      val func = "p !!" #> <span class="replacement">10</span>
+      val res = func.apply(<p class="first second">Test</p>)
+      (res \ "@class").text must_== "replacement"
+    }
+
+    "merge other attributes when using don't merge class modification" in {
+      val func = "p !!" #> <span data-two="2" class="replacement">10</span>
+      val res = func.apply(<p data-one="1" class="first second">Test</p>)
+      (res \ "@data-one").text must_== "1"
+      (res \ "@data-two").text must_== "2"
+      (res \ "@class").text must_== "replacement"
+    }
 
+    "leave node class attribute for replacement without class" in {
+      // TODO: Since was agreed not to change current behaviour, create test for it (https://groups.google.com/forum/#!topic/liftweb/Nswcxoykspc)
+      val func = "p !!" #> <span>10</span>
+      val res = func.apply(<p class="first second">Test</p>)
+      (res \ "@class").text must_== "first second"
+    }
 
     "Remove a subnode's class attribute" in {
 

docs/css-selectors.adoc

@@ -266,14 +266,15 @@ Remove from attribute rule: `[attribute-name!]`::
   its own separated by a space. For example, `^ [class!]` will remove the
   class named by the transformation result from all root elements.
 
-Don't merge attributes rule: `!!`::
+Don't merge class attribute rule: `!!`::
   By default, if the transformation yields a single element and the element
   matched by the selector is being replaced by that result, the attributes from
   the matched element are merged into the attributes of the transformation's
-  element. This modifier prevents that from happening. For example, by default
-  doing `"input" #> <div />` and applying it to `<input type="text">` would
-  yield `<div type="text" />`. Doing `"input !!" #> <div />` would instead yield
-  `<div />`.
+  element. This modifier prevents *ONLY* class attribute merging from happening.
+  For example, by default doing `"input" #> <div class="c1"/>` and applying it to
+  `<input class="c2" type="text"/>` would yield `<div type="text" class="c1 c2"/>`.
+  Doing `"input !!" #> <div class="c1" />` would instead yield
+  `<div type="text" class="c1"/>`.
 
 Lift node rule: `^^`::
   This rule will lift the first selected element all the way to the root of the