Revert of don't create zero length intervals (patchset #1 id:1 of https://codereview.chromium.org/1766243004/ )

Reason for revert:
This may, or may not, be blocking the DEPS roll with:

svg/W3C-SVG-1.1/painting-stroke-04-t.svg

-      LayoutSVGPath {path} at (50,127) size 380x26 [stroke={[type=SOLID] [color=#000000] [stroke width=25.00] [dash offset=10.00] [dash array={10.00, 10.00}]}] [data="M 50 140 L 430 140"]
+      LayoutSVGPath {path} at (60,127) size 370x26 [stroke={[type=SOLID] [color=#000000] [stroke width=25.00] [dash offset=10.00] [dash array={10.00, 10.00}]}] [data="M 50 140 L 430 140"]

Original issue's description:
> don't create zero length intervals
>
> Dashing a pattern without zero-length intervals should
> not create them if the end of the on interval coincides
> with the beginning of the initial dash offset.
>
> R=reed@google.com
> BUG=591993
> GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1766243004
>
> Committed: https://skia.googlesource.com/skia/+/18bbd00190623fb6cdb119df4a118ac3c1aed52a

TBR=reed@google.com,fmalita@chromium.org,caryclark@google.com
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=591993

Review URL: https://codereview.chromium.org/1779803002

2 files changed, 3 insertions, 17 deletions

diff --git a/gm/bug530095.cpp b/gm/bug530095.cpp
index 76f6bc8f2e..690da3c9d0 100644
--- a/gm/bug530095.cpp
+++ b/gm/bug530095.cpp
@@ -46,16 +46,3 @@ DEF_SIMPLE_GM(bug530095, canvas, 900, 1200) {
     canvas->translate(4, 4);
     canvas->drawPath(path2, paint);
 }
-
-DEF_SIMPLE_GM(bug591993, canvas, 40, 140) {
-    SkPaint p;
-    p.setColor(SK_ColorRED);
-    p.setAntiAlias(true);
-    p.setStyle(SkPaint::kStroke_Style);
-    p.setStrokeCap(SkPaint::kRound_Cap);
-    p.setStrokeWidth(10);
-    SkScalar intervals[] = { 100, 100 };
-    SkPathEffect* dash = SkDashPathEffect::Create(intervals, SK_ARRAY_COUNT(intervals), 100);
-    p.setPathEffect(dash)->unref();
-    canvas->drawLine(20, 20, 120, 20, p);
-}
diff --git a/src/utils/SkDashPath.cpp b/src/utils/SkDashPath.cpp
index 0d2783eba2..cd01a9972b 100644
--- a/src/utils/SkDashPath.cpp
+++ b/src/utils/SkDashPath.cpp
@@ -16,12 +16,11 @@ static inline int is_even(int x) {
 static SkScalar find_first_interval(const SkScalar intervals[], SkScalar phase,
                                     int32_t* index, int count) {
     for (int i = 0; i < count; ++i) {
-        SkScalar gap = intervals[i];
-        if (phase > gap || (phase == gap && gap)) {
-            phase -= gap;
+        if (phase > intervals[i]) {
+            phase -= intervals[i];
         } else {
             *index = i;
-            return gap - phase;
+            return intervals[i] - phase;
         }
     }
     // If we get here, phase "appears" to be larger than our length. This