[wasm] Change the constant kV8MaxWasmMemoryPages to a command line flag.

src/flag-definitions.h

Index: src/flag-definitions.h
diff --git a/src/flag-definitions.h b/src/flag-definitions.h
index 0d06b059e09c320365a882be46dbdf8ed924d501..dadf53acdc1b1bbe630f6129bbc820070d679276 100644
--- a/src/flag-definitions.h
+++ b/src/flag-definitions.h
@@ -499,6 +499,7 @@ DEFINE_NEG_IMPLICATION(minimal, use_ic)
 DEFINE_BOOL(expose_wasm, true, "expose WASM interface to JavaScript")
 DEFINE_INT(wasm_num_compilation_tasks, 10,
            "number of parallel compilation tasks for wasm")
+DEFINE_INT(wasm_max_mem_pages, 16384, "maximum memory size of a wasm instance")

[titzer, 2017/01/13 14:54:22]

You can actually define this as a uint32_t (which will save you all the casts
elsewhere), but it will parse (in flags.cc) as an int. Since we are already
doing a static_cast<int> there, we might actually already have a bug there if
someone passes a negative number or an out-of-range number. Or you could try to
introduce unsigned types to flags.cc...

[ahaas, 2017/01/17 09:09:55]

I think I did that now, but I'm not sure how flags.cc works in detail.

 DEFINE_BOOL(trace_wasm_encoder, false, "trace encoding of wasm code")
 DEFINE_BOOL(trace_wasm_decoder, false, "trace decoding of wasm code")
 DEFINE_BOOL(trace_wasm_decode_time, false, "trace decoding time of wasm code")