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

Source/platform/text/DateTimeFormat.cpp

Index: Source/platform/text/DateTimeFormat.cpp
diff --git a/Source/platform/text/DateTimeFormat.cpp b/Source/platform/text/DateTimeFormat.cpp
index 7ea210188fefd4656ca036b62117273e487f2147..1af63ea10f04422d43ca485b6b9a430ef9994e0f 100644
--- a/Source/platform/text/DateTimeFormat.cpp
+++ b/Source/platform/text/DateTimeFormat.cpp
@@ -256,21 +256,21 @@ void DateTimeFormat::quoteAndAppendLiteral(const String& literal, StringBuilder&
     }
 
     if (literal.find('\'') == kNotFound) {
-        buffer.append("'");
+        buffer.append('\'');
         buffer.append(literal);
-        buffer.append("'");
+        buffer.append('\'');
         return;
     }
 
     for (unsigned i = 0; i < literal.length(); ++i) {
         if (literal[i] == '\'') {
-            buffer.append("''");
+            buffer.appendLiteral("''");
         } else {
             String escaped = literal.substring(i);
             escaped.replace("'", "''");
-            buffer.append("'");
+            buffer.append('\'');
             buffer.append(escaped);
-            buffer.append("'");
+            buffer.append('\'');
             return;
         }
     }