Bug 1678756 - Check for new clusters or ligature groups in textPaths even in skipped characters r=emilio

The textcase and reference differ by a single space.
We should check for new clusters or ligature groups in textPaths even in skipped characters
Also removes a redundant check presumably left over from some earlier refactoring.

Differential Revision: https://phabricator.services.mozilla.com/D97828

layout/reftests/svg/text/reftest.list

@@ -114,6 +114,7 @@ random-if(/^Windows\x20NT\x206\.1/.test(http.oscpu)) fuzzy-if(skiaContent,0-1,0-
 random-if(/^Windows\x20NT\x206\.1/.test(http.oscpu)) == textpath-a.svg textpath-a-ref.svg # Bug 1392106
 random-if(/^Windows\x20NT\x206\.1/.test(http.oscpu)) == textpath-anchor-middle.svg textpath-anchor-middle-ref.svg # Bug 1392106
 random-if(/^Windows\x20NT\x206\.1/.test(http.oscpu)) == textpath-anchor-end.svg textpath-anchor-end-ref.svg # Bug 1392106
+random-if(/^Windows\x20NT\x206\.1/.test(http.oscpu)) == textpath-cluster.svg textpath-cluster-ref.svg # Bug 1392106
 random-if(/^Windows\x20NT\x206\.1/.test(http.oscpu)) == textpath-invalid-parent.svg textpath-invalid-parent-ref.svg # Bug 1392106
 random-if(/^Windows\x20NT\x206\.1/.test(http.oscpu)) == textpath-multiline.svg textpath-multiline-ref.svg # Bug 1392106
 random-if(/^Windows\x20NT\x206\.1/.test(http.oscpu)) == textpath-multiline-2.svg textpath-multiline-2-ref.svg # Bug 1392106

layout/reftests/svg/text/textpath-cluster-ref.svg

@@ -0,0 +1,12 @@
+<svg width="500" height="500" xmlns="http://www.w3.org/2000/svg" >
+  <defs>
+    <path id="path" d="M 100 200 C 200 100 300 0 400 100" />
+    <style>
+      text {
+        font: 40px monospace;
+      }
+    </style>
+  </defs>
+
+  <text transform="translate(0, 40)">a <textPath href="#path">b </textPath>c</text>
+</svg>

layout/reftests/svg/text/textpath-cluster.svg

@@ -0,0 +1,12 @@
+<svg width="500" height="500" xmlns="http://www.w3.org/2000/svg" >
+  <defs>
+    <path id="path" d="M 100 200 C 200 100 300 0 400 100" />
+    <style>
+      text {
+        font: 40px monospace;
+      }
+    </style>
+  </defs>
+
+  <text transform="translate(0, 40)">a <textPath href="#path">b </textPath> c</text>
+</svg>

layout/svg/SVGTextFrame.cpp

@@ -4661,8 +4661,7 @@ void SVGTextFrame::DoTextPathLayout() {
     }
 
     // Loop for each character in the text path.
-    while (!it.AtEnd() && it.TextPathFrame() &&
-           it.TextPathFrame()->GetContent() == textPath) {
+    while (!it.AtEnd() && it.TextPathFrame()) {
       // The index of the cluster or ligature group's first character.
       uint32_t i = it.TextElementCharIndex();
 
@@ -4694,11 +4693,10 @@ void SVGTextFrame::DoTextPathLayout() {
         // that's OK; we'll consider any complete cluster or ligature
         // group that begins inside the text path as being affected
         // by it.
-        if (it.IsOriginalCharSkipped()) {
-          // Leave partialAdvance unchanged.
-        } else if (it.IsClusterAndLigatureGroupStart()) {
+        if (it.IsClusterAndLigatureGroupStart()) {
           break;
-        } else {
+        }
+        if (!it.IsOriginalCharSkipped()) {
           partialAdvance += it.GetAdvance(context);
         }
         partialAdvances.AppendElement(partialAdvance);