[WebKit] Browsermark DomAdvSearch and DomSearch optimizations

        This patch is a combination of the following optimizations.

        Optimize appendCharactersReplacingEntities

        [Performance] Optimize innerHTML and outerHTML
        https://bugs.webkit.org/show_bug.cgi?id=81214

        Optimize Dromaeo/dom-query.html by caching NodeRareData on Document
        https://bugs.webkit.org/show_bug.cgi?id=90059

        Optimize Dromaeo/dom-attr.html by speeding up Element::getAttribute()
        https://bugs.webkit.org/show_bug.cgi?id=90174

        Change argument types of Element::getAttribute*() from String to AtomicString
        https://bugs.webkit.org/show_bug.cgi?id=90246

Conflicts:

	Source/WebCore/ChangeLog
	Source/WebCore/dom/Document.cpp
	Source/WebCore/dom/Document.h

Conflicts:

	Source/WebCore/ChangeLog

Change-Id: I9ca3d2e883155e2ad08c3cb0c5912b935ebe9406

1 files changed, 29 insertions, 0 deletions

diff --git a/Source/JavaScriptCore/wtf/text/StringBuilder.h b/Source/JavaScriptCore/wtf/text/StringBuilder.h
index f10af64..e891932 100644
--- a/Source/JavaScriptCore/wtf/text/StringBuilder.h
+++ b/Source/JavaScriptCore/wtf/text/StringBuilder.h
@@ -43,6 +43,9 @@ public:
 
     void append(const String& string)
     {
+        if (!string.length())
+            return;
+
         // If we're appending to an empty string, and there is not buffer
         // (in case reserveCapacity has been called) then just retain the
         // string.
@@ -54,6 +57,22 @@ public:
         append(string.characters(), string.length());
     }
 
+    void append(const StringBuilder& other)
+    {
+        if (!other.m_length)
+            return;
+
+        // If we're appending to an empty string, and there is not a buffer (reserveCapacity has not been called)
+        // then just retain the string.
+        if (!m_length && !m_buffer && !other.m_string.isNull()) {
+            m_string = other.m_string;
+            m_length = other.m_length;
+            return;
+        }
+
+        append(other.characters(), other.m_length);
+    }
+
     void append(const char* characters)
     {
         if (characters)
@@ -114,6 +133,16 @@ public:
         return m_buffer->characters()[i];
     }
 
+    const UChar* characters() const
+    {
+        if (!m_length)
+            return 0;
+        if (!m_string.isNull())
+            return m_string.characters();
+        ASSERT(m_buffer);
+        return m_buffer->characters();
+    }
+
     void clear()
     {
         m_length = 0;