[wasm] Support undefined indirect table entries, behind a flag.

src/wasm/wasm-opcodes.h

Index: src/wasm/wasm-opcodes.h
diff --git a/src/wasm/wasm-opcodes.h b/src/wasm/wasm-opcodes.h
index 764c5030f5f735554273c8f52780c6dfb805990a..bf64a08922a7686d4b976e1e1a89b67371db3e92 100644
--- a/src/wasm/wasm-opcodes.h
+++ b/src/wasm/wasm-opcodes.h
@@ -327,14 +327,15 @@ enum WasmOpcode {
 
 // The reason for a trap.
 #define FOREACH_WASM_TRAPREASON(V) \
-  V(TrapUnreachable)          \
-  V(TrapMemOutOfBounds)       \
-  V(TrapDivByZero)            \
-  V(TrapDivUnrepresentable)   \
-  V(TrapRemByZero)            \
-  V(TrapFloatUnrepresentable) \
-  V(TrapFuncInvalid)          \
-  V(TrapFuncSigMismatch)
+  V(TrapUnreachable)               \
+  V(TrapMemOutOfBounds)            \
+  V(TrapDivByZero)                 \
+  V(TrapDivUnrepresentable)        \
+  V(TrapRemByZero)                 \
+  V(TrapFloatUnrepresentable)      \
+  V(TrapFuncInvalid)               \
+  V(TrapFuncSigMismatch)           \
+  V(TrapDefaultFuncCall)
 
 enum TrapReason {
 #define DECLARE_ENUM(name) k##name,