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

Source/core/inspector/InspectorFileSystemAgent.cpp

Index: Source/core/inspector/InspectorFileSystemAgent.cpp
diff --git a/Source/core/inspector/InspectorFileSystemAgent.cpp b/Source/core/inspector/InspectorFileSystemAgent.cpp
old mode 100644
new mode 100755
index e406a22b8eeeae5df8b918122c72c5f8333d4d45..aa6798b86279581564d1275db78f5496bd628a2f
--- a/Source/core/inspector/InspectorFileSystemAgent.cpp
+++ b/Source/core/inspector/InspectorFileSystemAgent.cpp
@@ -490,8 +490,7 @@ void FileContentRequest::didRead()
     }
 
     OwnPtr<TextResourceDecoder> decoder = TextResourceDecoder::create(m_mimeType, m_charset, true);
-    String result = decoder->decode(static_cast<char*>(buffer->data()), buffer->byteLength());
-    result.append(decoder->flush());
+    String result = decoder->decode(static_cast<char*>(buffer->data()), buffer->byteLength()) + decoder->flush();
     m_charset = decoder->encoding().name();
     reportResult(static_cast<FileError::ErrorCode>(0), &result, &m_charset);
 }