--- a/dom/base/nsRange.cpp
+++ b/dom/base/nsRange.cpp
@@ -2901,16 +2901,23 @@ GetTextFrameForContent(nsIContent* aCont
 static nsresult GetPartialTextRect(nsLayoutUtils::RectCallback* aCallback,
                                    Sequence<nsString>* aTextList,
                                    nsIContent* aContent, int32_t aStartOffset,
                                    int32_t aEndOffset, bool aClampToEdge,
                                    bool aFlushLayout)
 {
   nsTextFrame* textFrame = GetTextFrameForContent(aContent, aFlushLayout);
   if (textFrame) {
+    // If we'll need it later, collect the full content text now.
+    nsAutoString textContent;
+    if (aTextList) {
+      mozilla::ErrorResult err; // ignored
+      aContent->GetTextContent(textContent, err);
+    }
+
     nsIFrame* relativeTo = nsLayoutUtils::GetContainingBlockForClientRect(textFrame);
     for (nsTextFrame* f = textFrame; f; f = static_cast<nsTextFrame*>(f->GetNextContinuation())) {
       int32_t fstart = f->GetContentOffset(), fend = f->GetContentEnd();
       if (fend <= aStartOffset || fstart >= aEndOffset)
         continue;
 
       // Calculate the text content offsets we'll need if text is requested.
       int32_t textContentStart = fstart;
@@ -2931,23 +2938,21 @@ static nsresult GetPartialTextRect(nsLay
         ExtractRectFromOffset(f, aEndOffset, &r, !rtl, aClampToEdge);
         textContentEnd = aEndOffset;
       }
       r = nsLayoutUtils::TransformFrameRectToAncestor(f, r, relativeTo);
       aCallback->AddRect(r);
 
       // Finally capture the text, if requested.
       if (aTextList) {
-        nsIFrame::RenderedText renderedText = f->GetRenderedText(
-          textContentStart,
-          textContentEnd,
-          nsIFrame::TextOffsetType::OFFSETS_IN_CONTENT_TEXT,
-          nsIFrame::TrailingWhitespace::DONT_TRIM_TRAILING_WHITESPACE);
-
-        aTextList->AppendElement(renderedText.mString, fallible);
+        const nsAString& textSubstring =
+          Substring(textContent,
+                    textContentStart,
+                    (textContentEnd - textContentStart));
+        aTextList->AppendElement(textSubstring, fallible);
       }
     }
   }
   return NS_OK;
 }
 
 /* static */ void
 nsRange::CollectClientRectsAndText(nsLayoutUtils::RectCallback* aCollector,

--- a/dom/base/test/chrome/test_range_getClientRectsAndTexts.html
+++ b/dom/base/test/chrome/test_range_getClientRectsAndTexts.html
@@ -10,27 +10,21 @@ SimpleTest.waitForExplicitFinish();
 
 function runTests()
 {
   let range = document.createRange();
 
   let attempts = [
     {startNode: "one", start:0, endNode:"one", end:0, textList:[], message:"Empty rect"},
     {startNode: "one", start:2, endNode:"one", end:6, textList:["l on"], message:"Single line"},
-    {startNode: "implicit", start:6, endNode:"implicit", end:12, textList:["it bre"], message:"Implicit break"},
+    {startNode: "implicit", start:6, endNode:"implicit", end:12, textList:["it\nbre"], message:"Implicit break"},
     {startNode: "two.a", start:1, endNode:"two.b", end:2, textList:["wo", "", "li"], message:"Two lines"},
     {startNode: "embed.a", start:7, endNode:"embed.b", end:2, textList:["th ", "simple nested", " ", "te"], message:"Simple nested"},
     {startNode: "deep.a", start:2, endNode:"deep.b", end:2, textList:["ne with ", "complex, more deeply nested", " ", "te"], message:"Complex nested"},
     {startNode: "image.a", start:7, endNode:"image.b", end:2, textList:["th inline ", "", " ", "im"], message:"Inline image"},
-    {startNode: "hyphen1", start:0, endNode:"hyphen1", end:3, textList:["a\u00AD", "b"], message:"Shy hyphen (active)"},
-    {startNode: "hyphen2", start:0, endNode:"hyphen2", end:3, textList:["c\u00ADd"], message:"Shy hyphen (inactive)"},
-    {startNode: "hyphen2", start:0, endNode:"hyphen2", end:2, textList:["c\u00AD"], message:"Shy hyphen (inactive, trailing)"},
-    {startNode: "hyphen2", start:1, endNode:"hyphen2", end:3, textList:["\u00ADd"], message:"Shy hyphen (inactive, leading)"},
-    {startNode: "uc", start:0, endNode:"uc", end:2, textList:["EF"], message:"UC transform"},
-    {startNode: "pre", start:0, endNode:"pre", end:3, textList:["g\n", "h"], message:"pre with break"},
   ];
 
   for (let attempt of attempts) {
     range.setStart(document.getElementById(attempt.startNode).childNodes[0], attempt.start);
     range.setEnd(document.getElementById(attempt.endNode).childNodes[0], attempt.end);
 
     let result = range.getClientRectsAndTexts();
 
@@ -57,19 +51,10 @@ break in one line</div>
 ><span id="two.b">lines</span></div>
 
 <div id="embed.a">Line with <span>simple nested</span> <span id="embed.b">text</span></div>
 
 <div id="deep.a">Line with <span>complex, <span>more <span>deeply <span>nested</span></span></span></span> <span id="deep.b">text</span></div>
 
 <div id="image.a">Line with inline <img src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABQAAAAUCAIAAAAC64paAAAAG0lEQVR42mP8z0A%2BYKJA76jmUc2jmkc1U0EzACKcASfOgGoMAAAAAElFTkSuQmCC" width="20" height="20"/> <span id="image.b">image</span></div>
 
-<div id="hyphen1" style="width:0">a&shy;b</div>
-
-<div id="hyphen2" style="width:100px">c&shy;d</div>
-
-<div id="uc" style="text-transform:uppercase">ef</div>
-
-<pre id="pre">g
-h</pre>
-
 </body>
 </html>
\ No newline at end of file

--- a/layout/base/nsLayoutUtils.cpp
+++ b/layout/base/nsLayoutUtils.cpp
@@ -4013,23 +4013,26 @@ struct MOZ_RAII BoxToRectAndText : publi
   static void AccumulateText(nsIFrame* aFrame, nsAString& aResult) {
     MOZ_ASSERT(aFrame);
 
     // Get all the text in aFrame and child frames, while respecting
     // the content offsets in each of the nsTextFrames.
     if (aFrame->GetType() == nsGkAtoms::textFrame) {
       nsTextFrame* textFrame = static_cast<nsTextFrame*>(aFrame);
 
-      nsIFrame::RenderedText renderedText = textFrame->GetRenderedText(
-        textFrame->GetContentOffset(),
-        textFrame->GetContentOffset() + textFrame->GetContentLength(),
-        nsIFrame::TextOffsetType::OFFSETS_IN_CONTENT_TEXT,
-        nsIFrame::TrailingWhitespace::DONT_TRIM_TRAILING_WHITESPACE);
-
-      aResult.Append(renderedText.mString);
+      nsIContent* content = textFrame->GetContent();
+      nsAutoString textContent;
+      mozilla::ErrorResult err; // ignored
+      content->GetTextContent(textContent, err);
+
+      const nsAString& textSubstring =
+        Substring(textContent,
+                  textFrame->GetContentOffset(),
+                  textFrame->GetContentLength());
+      aResult.Append(textSubstring);
     }
 
     for (nsIFrame* child = aFrame->PrincipalChildList().FirstChild();
          child;
          child = child->GetNextSibling()) {
       AccumulateText(child, aResult);
     }
   }