Clamp radial gradient end radii

Ensure that the end radius stays within finite float range, to
avoid degenerate cases down the line.

BUG=616993
R=fs@opera.com

Review-Url: https://codereview.chromium.org/2041653002
Cr-Commit-Position: refs/heads/master@{#398029}

third_party/WebKit/LayoutTests/fast/gradients/radial-clamping-expected.txt

+        PASS: did not crash.

third_party/WebKit/LayoutTests/fast/gradients/radial-clamping.html

+<DOCTYPE html>
+
+<style>
+div {
+    display: inline-block;
+    margin: 10px;
+    width: 400px;
+    height: 100px;
+}
+
+.r1 {
+    background-image: repeating-radial-gradient(closest-corner ellipse at -184467440737095516150000000000000000000% 37%, red, green);
+}
+
+.r2 {
+    background-image: repeating-radial-gradient(farthest-corner ellipse at -184467440737095516150000000000000000000% 37%, red, green);
+}
+
+.r3 {
+    background-image: repeating-radial-gradient(closest-side ellipse at -184467440737095516150000000000000000000% 37%, red, green);
+}
+
+.r4 {
+    background-image: repeating-radial-gradient(farthest-side ellipse at -184467440737095516150000000000000000000% 37%, red, green);
+}
+
+.r5 {
+    background-image: repeating-radial-gradient(closest-corner ellipse at 184467440737095516150000000000000000000% 37%, red, green);
+}
+
+.r6 {
+    background-image: repeating-radial-gradient(farthest-corner ellipse at 184467440737095516150000000000000000000% 37%, red, green);
+}
+
+.r7 {
+    background-image: repeating-radial-gradient(closest-side ellipse at 184467440737095516150000000000000000000% 37%, red, green);
+}
+
+.r8 {
+    background-image: repeating-radial-gradient(farthest-side ellipse at 184467440737095516150000000000000000000% 37%, red, green);
+}
+
+</style>
+
+<div class="r1"></div>
+<div class="r2"></div>
+<div class="r3"></div>
+<div class="r4"></div>
+<div class="r5"></div>
+<div class="r6"></div>
+<div class="r7"></div>
+<div class="r8"></div>
+
+PASS: did not crash.
+
+<script>
+  if (window.testRunner)
+    testRunner.dumpAsText();
+</script>

third_party/WebKit/Source/core/css/CSSGradientValue.cpp

@@ -1033,10 +1033,10 @@ enum EndShapeType {
 FloatSize radiusToSide(const FloatPoint& point, const FloatSize& size, EndShapeType shape,
     bool (*compare)(float, float))
 {
-    float dx1 = fabs(point.x());
-    float dy1 = fabs(point.y());
-    float dx2 = fabs(point.x() - size.width());
-    float dy2 = fabs(point.y() - size.height());
+    float dx1 = clampTo<float>(fabs(point.x()));
+    float dy1 = clampTo<float>(fabs(point.y()));
+    float dx2 = clampTo<float>(fabs(point.x() - size.width()));
+    float dy2 = clampTo<float>(fabs(point.y() - size.height()));
 
     float dx = compare(dx1, dx2) ? dx1 : dx2;
     float dy = compare(dy1, dy2) ? dy1 : dy2;
@@ -1056,7 +1056,7 @@ inline FloatSize ellipseRadius(const FloatPoint& p, float aspectRatio)
     // a/b = aspectRatio, b = a/aspectRatio
     // a = sqrt(x^2 + y^2/(1/r^2))
     float a = sqrtf(p.x() * p.x() + p.y() * p.y() * aspectRatio * aspectRatio);
-    return FloatSize(a, a / aspectRatio);
+    return FloatSize(clampTo<float>(a), clampTo<float>(a / aspectRatio));
 }
 
 // Compute the radius to the closest/farthest corner (depending on the compare functor).
@@ -1153,6 +1153,10 @@ PassRefPtr<Gradient> CSSRadialGradientValue::createGradient(const CSSToLengthCon
         }
     }
 
+    DCHECK(std::isfinite(firstRadius));
+    DCHECK(std::isfinite(secondRadius.width()));
+    DCHECK(std::isfinite(secondRadius.height()));
+
     bool isDegenerate = !secondRadius.width() || !secondRadius.height();
     RefPtr<Gradient> gradient = Gradient::create(firstPoint, firstRadius, secondPoint,
         isDegenerate ? 0 : secondRadius.width(), isDegenerate ? 1 : secondRadius.aspectRatio());