v8: avoid unnecessary log level checks. (#146)
v8: avoid unnecessary log level checks. (#146)

It's mostly a pedantic change, but it slightly improves performance
in microbenchmarks.

Benchmark                                                       Diff
--------------------------------------------------------------------
WasmSpeedTest_empty                                          -0.0891
WasmSpeedTest_get_current_time                               -0.0424
WasmSpeedTest_small_string                                   -0.0507
WasmSpeedTest_small_string1000                               -0.0118
WasmSpeedTest_small_string_check_compiler                    -0.0556
WasmSpeedTest_small_string_check_compiler1000                +0.0041
WasmSpeedTest_large_string                                   -0.0322
WasmSpeedTest_large_string1000                               -0.0311
WasmSpeedTest_get_property                                   -0.0173
WasmSpeedTest_grpc_service                                   -0.0558
WasmSpeedTest_grpc_service1000                               -0.0021
WasmSpeedTest_modify_metadata                                +0.0410
WasmSpeedTest_modify_metadata1000                            -0.0298
WasmSpeedTest_json_serialize                                 +0.0009
WasmSpeedTest_json_deserialize                               +0.0028
WasmSpeedTest_json_deserialize_empty                         -0.0028
WasmSpeedTest_convert_to_filter_state                        -0.0172

Signed-off-by: Piotr Sikora <ba6f3a1a6d7e1ecae91b31e93969cc392fbd0fdd@google.com>
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