Mark AtomicString(StringImpl*) constructor as explicit

Source/wtf/text/AtomicString.h

Index: Source/wtf/text/AtomicString.h
diff --git a/Source/wtf/text/AtomicString.h b/Source/wtf/text/AtomicString.h
index 698f4ca9aecba0b9d941c18b6b0a88a9b813595f..7e3e6b8e133f033bd099b6a772acf72dbfa6d18a 100644
--- a/Source/wtf/text/AtomicString.h
+++ b/Source/wtf/text/AtomicString.h
@@ -55,7 +55,7 @@ public:
     {
     }
 
-    ATOMICSTRING_CONVERSION AtomicString(StringImpl* imp) : m_string(add(imp)) { }
+    explicit AtomicString(StringImpl* imp) : m_string(add(imp)) { }

[eseidel, 2013/11/27 20:21:00]

So previously this was optionally (compile time) explicit, and now it's always
explicit, right?

[Inactive, 2013/11/27 20:33:25]

This is correct. 

     ATOMICSTRING_CONVERSION AtomicString(const String& s) : m_string(add(s.impl())) { }
     AtomicString(StringImpl* baseString, unsigned start, unsigned length) : m_string(add(baseString, start, length)) { }