Web Audio: Add support for variable buffer sizes to Audio Worklets.

Support for this was added to Emscripten 3.1.70. Currently only
querying the quantum size is supported. I believe support for
configuring the quantum size is coming later in Web Audio 1.1.

Compilation with versions of Emscripten earlier than 3.1.70 is still
supported.

miniaudio.h

@@ -39857,6 +39857,10 @@ Web Audio Backend
 #if (__EMSCRIPTEN_major__ > 3) || (__EMSCRIPTEN_major__ == 3 && (__EMSCRIPTEN_minor__ > 1 || (__EMSCRIPTEN_minor__ == 1 && __EMSCRIPTEN_tiny__ >= 32)))
     #include <emscripten/webaudio.h>
     #define MA_SUPPORT_AUDIO_WORKLETS
+
+    #if (__EMSCRIPTEN_major__ > 3) || (__EMSCRIPTEN_major__ == 3 && (__EMSCRIPTEN_minor__ > 1 || (__EMSCRIPTEN_minor__ == 1 && __EMSCRIPTEN_tiny__ >= 70)))
+        #define MA_SUPPORT_AUDIO_WORKLETS_VARIABLE_BUFFER_SIZE
+    #endif
 #endif
 
 /*
@@ -40112,7 +40116,11 @@ static EM_BOOL ma_audio_worklet_process_callback__webaudio(int inputCount, const
     Unfortunately the audio data is not interleaved so we'll need to convert it before we give the data to miniaudio
     for further processing.
     */
-    frameCount = 128;
+    if (pDevice->type == ma_device_type_playback) {
+        frameCount = pDevice->playback.internalPeriodSizeInFrames;
+    } else {
+        frameCount = pDevice->capture.internalPeriodSizeInFrames;
+    }
 
     if (ma_device_get_state(pDevice) != ma_device_state_started) {
         /* Fill the output buffer with zero to avoid a noise sound */
@@ -40199,7 +40207,15 @@ static void ma_audio_worklet_processor_created__webaudio(EMSCRIPTEN_WEBAUDIO_T a
     Now that we know the channel count to use we can allocate the intermediary buffer. The
     intermediary buffer is used for interleaving and deinterleaving.
     */
+    #if defined(MA_SUPPORT_AUDIO_WORKLETS_VARIABLE_BUFFER_SIZE)
+    {
+        intermediaryBufferSizeInFrames = (size_t)emscripten_audio_context_quantum_size(audioContext);
+    }
+    #else
+    {
         intermediaryBufferSizeInFrames = 128;
+    }
+    #endif
 
     pParameters->pDevice->webaudio.pIntermediaryBuffer = (float*)ma_malloc(intermediaryBufferSizeInFrames * (ma_uint32)channels * sizeof(float), &pParameters->pDevice->pContext->allocationCallbacks);
     if (pParameters->pDevice->webaudio.pIntermediaryBuffer == NULL) {