Prevent LayoutTest setting -1 page scale factor.

third_party/WebKit/Source/core/testing/Internals.cpp

Index: third_party/WebKit/Source/core/testing/Internals.cpp
diff --git a/third_party/WebKit/Source/core/testing/Internals.cpp b/third_party/WebKit/Source/core/testing/Internals.cpp
index 5420021b8ae163c2b7c9301edd74d4f079612e0b..50c5e1b56a560945c6d539674bd95fd56cad5717 100644
--- a/third_party/WebKit/Source/core/testing/Internals.cpp
+++ b/third_party/WebKit/Source/core/testing/Internals.cpp
@@ -1878,6 +1878,8 @@ float Internals::pageScaleFactor(ExceptionState& exceptionState)
 
 void Internals::setPageScaleFactor(float scaleFactor, ExceptionState& exceptionState)
 {
+    if (scaleFactor <= 0)
+        return;
     Document* document = contextDocument();
     if (!document || !document->page()) {
         exceptionState.throwDOMException(InvalidAccessError, document ? "The document's page cannot be retrieved." : "No context document can be obtained.");