Bug 1765162 - Fix leak in GlyphCacheEntry. r=aosmond

GlyphBuffer was getting allocated but never destroyed.
This adds a destructor that fixes that.

Differential Revision: https://phabricator.services.mozilla.com/D143917

dom/canvas/DrawTargetWebgl.cpp

@@ -2266,6 +2266,8 @@ GlyphCacheEntry::GlyphCacheEntry(const GlyphBuffer& aBuffer,
   mBuffer.mNumGlyphs = aBuffer.mNumGlyphs;
 }
 
+GlyphCacheEntry::~GlyphCacheEntry() { delete[] mBuffer.mGlyphs; }
+
 // Attempt to find a matching entry in the glyph cache. If one isn't found,
 // a new entry will be created. The caller should check whether the contained
 // texture handle is valid to determine if it will need to render the text run

dom/canvas/DrawTargetWebglInternal.h

@@ -302,6 +302,7 @@ class GlyphCacheEntry : public CacheEntryImpl<GlyphCacheEntry> {
   GlyphCacheEntry(const GlyphBuffer& aBuffer, const DeviceColor& aColor,
                   const Matrix& aTransform, const IntRect& aBounds,
                   HashNumber aHash);
+  ~GlyphCacheEntry();
 
   bool MatchesGlyphs(const GlyphBuffer& aBuffer, const DeviceColor& aColor,
                      const Matrix& aTransform, const IntRect& aBounds,