Remove 'String::append' from some of the blink source.

Source/core/fetch/FontResource.cpp

Index: Source/core/fetch/FontResource.cpp
diff --git a/Source/core/fetch/FontResource.cpp b/Source/core/fetch/FontResource.cpp
old mode 100644
new mode 100755
index 0fdbcc1d39e9a76f602f07f8dc2a14315522a5f4..8e342af8f4df6eb3b7c7c437d465cafec9affee5
--- a/Source/core/fetch/FontResource.cpp
+++ b/Source/core/fetch/FontResource.cpp
@@ -110,8 +110,7 @@ bool FontResource::ensureSVGFontData()
             m_externalSVGDocument = SVGDocument::create();
 
             OwnPtr<TextResourceDecoder> decoder = TextResourceDecoder::create("application/xml");
-            String svgSource = decoder->decode(m_data->data(), m_data->size());
-            svgSource.append(decoder->flush());
+            String svgSource = decoder->decode(m_data->data(), m_data->size()) + decoder->flush();
 
             m_externalSVGDocument->setContent(svgSource);