Fix crash when inserting empty path

The path creation method begins with an open MoveTo point. If nothing
else is added, CFX_PathData::GetBoundingBox will try an OOB access in
its m_Points. This CL adds a check similar to the one in
CPDF_StreamContentParser::AddPathObject.
Change-Id: Iec7cfe3379253c021ba7d5f276306a66009f84e2
Reviewed-on: https://pdfium-review.googlesource.com/6593
Commit-Queue: Nicolás Peña <npm@chromium.org>
Commit-Queue: dsinclair <dsinclair@chromium.org>
Reviewed-by: dsinclair <dsinclair@chromium.org>
diff --git a/fpdfsdk/fpdfedit_embeddertest.cpp b/fpdfsdk/fpdfedit_embeddertest.cpp
index 1146a8c..f7bade9 100644
--- a/fpdfsdk/fpdfedit_embeddertest.cpp
+++ b/fpdfsdk/fpdfedit_embeddertest.cpp
@@ -593,13 +593,12 @@
   EXPECT_EQ(2, static_cast<int>(graphics_dict->GetCount()));
 
   // Add a path that should reuse graphics
-  // TODO(npm): This causes a crash on Windows.
-  /*FPDF_PAGEOBJECT path = FPDFPageObj_CreateNewPath(400, 100);
+  FPDF_PAGEOBJECT path = FPDFPageObj_CreateNewPath(400, 100);
   FPDFPageObj_SetBlendMode(path, "Darken");
   EXPECT_TRUE(FPDFPath_SetFillColor(path, 200, 200, 100, 150));
   FPDFPage_InsertObject(page.get(), path);
   EXPECT_TRUE(FPDFPage_GenerateContent(page.get()));
-  EXPECT_EQ(2, static_cast<int>(graphics_dict->GetCount()));*/
+  EXPECT_EQ(2, static_cast<int>(graphics_dict->GetCount()));
 
   // Add a rect increasing the size of the graphics dictionary
   FPDF_PAGEOBJECT rect2 = FPDFPageObj_CreateNewRect(10, 10, 100, 100);