WindowFeatures arguments shoud ignore invalid characters in values

Source/core/page/WindowFeatures.cpp

Index: Source/core/page/WindowFeatures.cpp
diff --git a/Source/core/page/WindowFeatures.cpp b/Source/core/page/WindowFeatures.cpp
index b5ecaa8adc06196904664b7197f954a2ee8462da..85202c251543a44a72e088eb7fef25c760ed0848 100644
--- a/Source/core/page/WindowFeatures.cpp
+++ b/Source/core/page/WindowFeatures.cpp
@@ -74,13 +74,12 @@ WindowFeatures::WindowFeatures(const String& features)
     scrollbarsVisible = false;
 
     // Tread lightly in this code -- it was specifically designed to mimic Win IE's parsing behavior.
-    int keyBegin, keyEnd;
-    int valueBegin, valueEnd;
+    unsigned keyBegin, keyEnd;
+    unsigned valueBegin, valueEnd;
 
-    int i = 0;
-    int length = features.length();
     String buffer = features.lower();
-    while (i < length) {
+    unsigned length = buffer.length();
+    for (unsigned i = 0; i < length; ) {
         // skip to first non-separator, but don't skip past the end of the string
         while (i < length && isWindowFeaturesSeparator(buffer[i]))
             i++;