[PE] Relax TransformationMatrix::IsInvertible

Previously it treated transforms with abs(determinant) less than 1e-8 as
non-invertible. This was too strict that transforms like Scale(9.9e-5)
were treated as non-invertible.

Now just check if determinant is zero, which is consistent with
AffineTransform and SkMatrix[44].

The code was added here:
https://chromium.googlesource.com/chromium/src/+/041f0d1e8d01d8dc0cd2f4fe2579e1f09a9ae27a
in an initial commit of 3D transforms.

Bug: 849382
Change-Id: I01e395f373493f61fcf85851b694be9aed7b41c5
Reviewed-on: https://chromium-review.googlesource.com/1087362
Commit-Queue: Xianzhu Wang <wangxianzhu@chromium.org>
Reviewed-by: Fredrik Söderquist <fs@opera.com>
Reviewed-by: Chris Harrelson <chrishtr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#564680}

third_party/blink/renderer/platform/transforms/transformation_matrix.cc

@@ -78,8 +78,6 @@ namespace blink {
 typedef double Vector4[4];
 typedef double Vector3[3];
 
-const double kSmallNumber = 1.e-8;
-
 // inverse(original_matrix, inverse_matrix)
 //
 // calculate the inverse of a 4x4 matrix
@@ -225,7 +223,7 @@ static bool Inverse(const TransformationMatrix::Matrix4& matrix,
   // then the inverse matrix is not unique.
   double det = Determinant4x4(matrix);
 
-  if (fabs(det) < kSmallNumber)
+  if (det == 0)
     return false;
 
 #if defined(ARCH_CPU_ARM64)
@@ -1651,15 +1649,7 @@ void TransformationMatrix::MultVecMatrix(double x,
 }
 
 bool TransformationMatrix::IsInvertible() const {
-  if (IsIdentityOrTranslation())
-    return true;
-
-  double det = blink::Determinant4x4(matrix_);
-
-  if (fabs(det) < kSmallNumber)
-    return false;
-
-  return true;
+  return IsIdentityOrTranslation() || blink::Determinant4x4(matrix_) != 0;
 }
 
 TransformationMatrix TransformationMatrix::Inverse() const {

third_party/blink/renderer/platform/transforms/transformation_matrix_test.cc

@@ -285,4 +285,15 @@ TEST(TransformationMatrixTest, ToString) {
             column_major_constructor.ToString(true));
 }
 
+TEST(TransformationMatrix, IsInvertible) {
+  EXPECT_FALSE(
+      TransformationMatrix(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0)
+          .IsInvertible());
+  EXPECT_TRUE(TransformationMatrix().IsInvertible());
+  EXPECT_TRUE(TransformationMatrix().Translate3d(10, 20, 30).IsInvertible());
+  EXPECT_TRUE(TransformationMatrix().Scale(1e-8).IsInvertible());
+  EXPECT_TRUE(TransformationMatrix().Scale3d(1e-8, -1e-8, 1).IsInvertible());
+  EXPECT_FALSE(TransformationMatrix().Scale(0).IsInvertible());
+}
+
 }  // namespace blink