Use RenderStyle::isCollapsibleWhiteSpace when renderer is available.

Source/core/editing/htmlediting.h

Index: Source/core/editing/htmlediting.h
diff --git a/Source/core/editing/htmlediting.h b/Source/core/editing/htmlediting.h
index 115ad0d6e6ad9739b206ab0f8d8700b6fdf20c1a..1c7b9fbc35ce2296be1b01e10c0bf11d9a6c36a2 100644
--- a/Source/core/editing/htmlediting.h
+++ b/Source/core/editing/htmlediting.h
@@ -245,6 +245,12 @@ inline bool isWhitespace(UChar c)
     return c == noBreakSpace || c == ' ' || c == '\n' || c == '\t';
 }
 
+// FIXME: Can't really answer this question correctly without knowing the white-space mode.
+inline bool isCollapsibleWhitespace(UChar c)
+{
+    return c == ' ' || c == '\n';
+}
+
 inline bool isAmbiguousBoundaryCharacter(UChar character)
 {
     // These are characters that can behave as word boundaries, but can appear within words.