[Android WebView] Treat zero values in viewport arguments specially

Source/core/dom/ViewportArguments.cpp

Index: Source/core/dom/ViewportArguments.cpp
diff --git a/Source/core/dom/ViewportArguments.cpp b/Source/core/dom/ViewportArguments.cpp
index 0a2708dd1f07b1b02f760d61f5acb4d501683393..d32836aaa10cd6f8adc73dd426b9d0f7400236f3 100644
--- a/Source/core/dom/ViewportArguments.cpp
+++ b/Source/core/dom/ViewportArguments.cpp
@@ -29,6 +29,8 @@
 #include "core/dom/ViewportArguments.h"
 
 #include "core/dom/Document.h"
+#include "core/page/Page.h"
+#include "core/page/Settings.h"
 #include "wtf/text/WTFString.h"
 
 using namespace std;
@@ -297,6 +299,13 @@ static float findSizeValue(const String& keyString, const String& valueString, D
     if (value < 0)
         return ViewportArguments::ValueAuto;
 
+    if (!static_cast<int>(value) && document->page() && document->page()->settings().viewportMetaZeroValuesQuirk()) {
+        if (keyString == "width")
+            return ViewportArguments::ValueDeviceWidth;
+        if (keyString == "height")
+            return ViewportArguments::ValueDeviceHeight;
+    }
+
     return value;
 }
 
@@ -325,6 +334,9 @@ static float findScaleValue(const String& keyString, const String& valueString,
     if (value > 10.0)
         reportViewportWarning(document, MaximumScaleTooLargeError, String(), String());
 
+    if (!static_cast<int>(value) && document->page() && document->page()->settings().viewportMetaZeroValuesQuirk() && (keyString == "minimum-scale" || keyString == "maximum-scale"))
+        return ViewportArguments::ValueAuto;
+
     return value;
 }