Landing pkasting's webrtc fixes for MSVC level 4 warnings in WebRTC.

---

Fixes for re-enabling more MSVC level 4 warnings: webrtc/ edition

This contains fixes for the following sorts of issues:
* Possibly-uninitialized local variable
* Signedness mismatch
* Assignment inside conditional

This also contains a small number of other cleanups to nearby code. In
particular several warning-disables for MSVC are removed because they don't seem
to be necessary (either that warning is not enabled or the code does not trigger
it).

BUG=crbug.com/81439
TEST=none
R=henrika@webrtc.org, pkasting@chromium.org

Review URL: https://webrtc-codereview.appspot.com/18769004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@6667 4adac7df-926f-26a2-2b94-8c16560cd09d

webrtc/modules/audio_coding/codecs/isac/main/source/isac.c

@@ -2243,8 +2243,6 @@ int16_t WebRtcIsac_SetEncSampRate(ISACStruct* ISAC_main_inst,
   } else {
     ISACUBStruct* instUB = &(instISAC->instUB);
     ISACLBStruct* instLB = &(instISAC->instLB);
-    double bottleneckLB;
-    double bottleneckUB;
     int32_t bottleneck = instISAC->bottleneck;
     int16_t codingMode = instISAC->codingMode;
     int16_t frameSizeMs = instLB->ISACencLB_obj.new_framelength /
@@ -2263,6 +2261,8 @@ int16_t WebRtcIsac_SetEncSampRate(ISACStruct* ISAC_main_inst,
       instISAC->maxRateBytesPer30Ms = STREAM_SIZE_MAX_30;
     } else if ((encoder_operational_rate == kIsacSuperWideband) &&
                (instISAC->encoderSamplingRateKHz == kIsacWideband)) {
+      double bottleneckLB = 0;
+      double bottleneckUB = 0;
       if (codingMode == 1) {
         WebRtcIsac_RateAllocation(bottleneck, &bottleneckLB, &bottleneckUB,
                                   &(instISAC->bandwidthKHz));