Fix uninitialized triangle in rendering.

core/src/fpdfapi/fpdf_render/fpdf_render_pattern.cpp

Index: core/src/fpdfapi/fpdf_render/fpdf_render_pattern.cpp
diff --git a/core/src/fpdfapi/fpdf_render/fpdf_render_pattern.cpp b/core/src/fpdfapi/fpdf_render/fpdf_render_pattern.cpp
index 0bf6311b1906d18da099b61c645658af5fc9dab9..926ce8883b7aed83ba21caf3dbcd3639c50739d7 100644
--- a/core/src/fpdfapi/fpdf_render/fpdf_render_pattern.cpp
+++ b/core/src/fpdfapi/fpdf_render/fpdf_render_pattern.cpp
@@ -389,6 +389,8 @@ static void _DrawFreeGouraudShading(CFX_DIBitmap* pBitmap, CFX_AffineMatrix* pOb
         return;
     }
     CPDF_MeshVertex triangle[3];
+    FXSYS_memset32(triangle, 0, sizeof(triangle));
+
     while (!stream.m_BitStream.IsEOF()) {
         CPDF_MeshVertex vertex;
         FX_DWORD flag = stream.GetVertex(vertex, pObject2Bitmap);