check for bad params sent to discrete patheffect

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1853953002

TBR=

Review URL: https://codereview.chromium.org/1853953002
diff --git a/src/effects/SkDiscretePathEffect.cpp b/src/effects/SkDiscretePathEffect.cpp
index 5af6ab4..1c6039c 100644
--- a/src/effects/SkDiscretePathEffect.cpp
+++ b/src/effects/SkDiscretePathEffect.cpp
@@ -14,6 +14,12 @@
 
 sk_sp<SkPathEffect> SkDiscretePathEffect::Make(SkScalar segLength, SkScalar deviation,
                                                uint32_t seedAssist) {
+    if (!SkScalarIsFinite(segLength) || !SkScalarIsFinite(deviation)) {
+        return nullptr;
+    }
+    if (segLength <= SK_ScalarNearlyZero) {
+        return nullptr;
+    }
     return sk_sp<SkPathEffect>(new SkDiscretePathEffect(segLength, deviation, seedAssist));
 }