Initialize VTTCue::m_displaySize to undefinedSize

Source/core/html/track/vtt/VTTCue.cpp

Index: Source/core/html/track/vtt/VTTCue.cpp
diff --git a/Source/core/html/track/vtt/VTTCue.cpp b/Source/core/html/track/vtt/VTTCue.cpp
index 2766960b9f0fa4d442ca5e489dd8ee91cc7fb3b9..f5a4c8cf7f7fb7e08de4d67aae04ddc74a170b38 100644
--- a/Source/core/html/track/vtt/VTTCue.cpp
+++ b/Source/core/html/track/vtt/VTTCue.cpp
@@ -54,6 +54,7 @@
 namespace WebCore {
 
 static const int undefinedPosition = -1;
+static const int undefinedSize = -1;
 
 static const CSSValueID displayWritingModeMap[] = {
     CSSValueHorizontalTb, CSSValueVerticalRl, CSSValueVerticalLr
@@ -212,6 +213,7 @@ VTTCue::VTTCue(Document& document, double startTime, double endTime, const Strin
     , m_vttNodeTree(0)
     , m_cueBackgroundBox(HTMLDivElement::create(document))
     , m_displayDirection(CSSValueLtr)
+    , m_displaySize(undefinedSize)
     , m_snapToLines(true)
     , m_displayTreeShouldChange(true)
     , m_notifyRegion(true)
@@ -1045,6 +1047,7 @@ CSSValueID VTTCue::getCSSWritingMode() const
 
 int VTTCue::getCSSSize() const
 {
+    ASSERT(m_displaySize != undefinedSize);
     return m_displaySize;
 }