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

Source/core/inspector/NetworkResourcesData.cpp

Index: Source/core/inspector/NetworkResourcesData.cpp
diff --git a/Source/core/inspector/NetworkResourcesData.cpp b/Source/core/inspector/NetworkResourcesData.cpp
old mode 100644
new mode 100755
index 7aaa47a174cddd03701e21077242cdebcdb0a4bb..e5edf295e38c159306c071baa0739471b8a80cde
--- a/Source/core/inspector/NetworkResourcesData.cpp
+++ b/Source/core/inspector/NetworkResourcesData.cpp
@@ -131,7 +131,7 @@ size_t NetworkResourcesData::ResourceData::decodeDataToContent()
     ASSERT(!hasContent());
     size_t dataLength = m_dataBuffer->size();
     m_content = m_decoder->decode(m_dataBuffer->data(), m_dataBuffer->size());
-    m_content.append(m_decoder->flush());
+    m_content = m_content + m_decoder->flush();
     m_dataBuffer = nullptr;
     return contentSizeInBytes(m_content) - dataLength;
 }