making string conversions explicit

xpcom/ds/nsPersistentProperties.cpp

@@ -135,7 +135,7 @@ nsPersistentProperties::Load(nsIInputStream *aIn)
             c = SkipWhiteSpace(c);
           }
           else {
-            value.Append('\\');
+            value.AppendWithConversion('\\');
           }
         }
         value.Append((PRUnichar) c);

xpcom/io/nsBinaryStream.cpp

@@ -303,10 +303,10 @@ nsBinaryInputStream::ReadStringZ(char* *aString)
         rv = Read(&c, 1, &actualBytesRead);
         if (NS_FAILED(rv) || actualBytesRead != 1)
             return NS_ERROR_FAILURE;
-        if (c)
-            result += c;
-        else
+        if (!c)
             break;
+
+        result.AppendWithConversion(c);
     }
 
     *aString = result.ToNewCString();