fix misc asserts and checks found by fuzzer

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1713383002

TBR=robertphilips

Review URL: https://codereview.chromium.org/1713383002

1 files changed, 14 insertions, 0 deletions

diff --git a/src/effects/SkDashPathEffect.cpp b/src/effects/SkDashPathEffect.cpp
index 6e10e5466d..ced0aab69a 100644
--- a/src/effects/SkDashPathEffect.cpp
+++ b/src/effects/SkDashPathEffect.cpp
@@ -384,3 +384,17 @@ void SkDashPathEffect::toString(SkString* str) const {
     str->appendf("))");
 }
 #endif
+
+//////////////////////////////////////////////////////////////////////////////////////////////////
+
+SkPathEffect* SkDashPathEffect::Create(const SkScalar intervals[], int count, SkScalar phase) {
+    if ((count < 2) || !SkIsAlign2(count)) {
+        return nullptr;
+    }
+    for (int i = 0; i < count; i++) {
+        if (intervals[i] < 0) {
+            return nullptr;
+        }
+    }
+    return new SkDashPathEffect(intervals, count, phase);
+}