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 60c2a8feec6f4f1492c842d4c58afce3fb38a49e..18585491a71dd01ab9e64728ec15c63c61bcd9c3
--- a/Source/core/inspector/NetworkResourcesData.cpp
+++ b/Source/core/inspector/NetworkResourcesData.cpp
@@ -34,6 +34,7 @@
 #include "platform/MIMETypeRegistry.h"
 #include "platform/SharedBuffer.h"
 #include "platform/network/ResourceResponse.h"
+#include "wtf/text/StringBuilder.h"
 
 namespace {
 // 100MB
@@ -130,8 +131,10 @@ 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());
+    StringBuilder content;
+    content.append(m_decoder->decode(m_dataBuffer->data(), m_dataBuffer->size()));
+    content.append(m_decoder->flush());
+    m_content = content.toString();
     m_dataBuffer = nullptr;
     return contentSizeInBytes(m_content) - dataLength;
 }