Use StringBuilder::appendLiteral() / StringBuilder::append(char) when possible

Source/core/inspector/InspectorStyleSheet.cpp

Index: Source/core/inspector/InspectorStyleSheet.cpp
diff --git a/Source/core/inspector/InspectorStyleSheet.cpp b/Source/core/inspector/InspectorStyleSheet.cpp
index 59438fcfff4e281a5fc906f459fc812a528bb463..6723208ccc0d91e159d3aa38101e390ba050c464 100644
--- a/Source/core/inspector/InspectorStyleSheet.cpp
+++ b/Source/core/inspector/InspectorStyleSheet.cpp
@@ -747,7 +747,7 @@ String InspectorStyle::shorthandValue(const String& shorthandProperty) const
             if (individualValue == "initial")
                 continue;
             if (!builder.isEmpty())
-                builder.append(" ");
+                builder.append(' ');
             builder.append(individualValue);
         }