[Wasm R2R] Report tracked GC vars as untracked in GC info (#129100)

The wasm JIT does not emit tracked GC slot lifetimes (noTrackedGCSlots
is true on wasm). Ensure any (liveness) tracked GC vars get reported as
untracked for GC purposes, and also get properly zero initialized.

Fixes some more cases in #128234.

Author: AndyAyersMS

src/coreclr/jit/codegencommon.cpp

@@ -3799,6 +3799,14 @@ void CodeGen::genCheckUseBlockInit()
                     JITDUMP("must init a tracked V%02u because it a struct with a GC ref\n", varNum);
                     mustInitThisVar = true;
                 }
+#ifdef TARGET_WASM
+                else if (hasGCPtr)
+                {
+                    // On wasm all GC vars are reported as untracked, so the slot must be zero-inited.
+                    JITDUMP("must init V%02u because wasm reports tracked GC vars as untracked\n", varNum);
+                    mustInitThisVar = true;
+                }
+#endif
                 else
                 {
                     // We are done with tracked or GC vars, now look at untracked vars without GC refs.

src/coreclr/jit/gcencode.cpp

@@ -4134,7 +4134,9 @@ void GCInfo::gcMakeRegPtrTable(
                 // If it is pinned, it must be an untracked local.
                 assert(!varDsc->lvPinned || !varDsc->lvTracked);
 
-                if (varDsc->lvTracked || !varDsc->lvOnFrame)
+                // When noTrackedGCSlots is true (e.g. on wasm) tracked on-frame GC vars
+                // must be reported here as untracked, since gcVarPtrList is not populated.
+                if ((varDsc->lvTracked && !noTrackedGCSlots) || !varDsc->lvOnFrame)
                 {
                     continue;
                 }
@@ -4161,7 +4163,9 @@ void GCInfo::gcMakeRegPtrTable(
                 }
                 else
                 {
-                    if (varDsc->lvIsRegArg && varDsc->lvTracked)
+                    // When noTrackedGCSlots is true (e.g. on wasm) tracked register args
+                    // must fall through and be reported as untracked.
+                    if (varDsc->lvIsRegArg && varDsc->lvTracked && !noTrackedGCSlots)
                     {
                         // If this register-passed arg is tracked, then
                         // it has been allocated space near the other