--- a/Source/WTF/wtf/text/icu/UTextProvider.h	
+++ a/Source/WTF/wtf/text/icu/UTextProvider.h	
@@ -79,12 +79,12 @@ inline bool uTextAccessInChunkOrOutOfRange(UText* text, int64_t nativeIndex, int
             // Ensure chunk offset is well formed if computed offset exceeds int32_t range.
             ASSERT(offset < std::numeric_limits<int32_t>::max());
             text->chunkOffset = offset < std::numeric_limits<int32_t>::max() ? static_cast<int32_t>(offset) : 0;
-            isAccessible = TRUE;
+            isAccessible = true;
             return true;
         }
         if (nativeIndex >= nativeLength && text->chunkNativeLimit == nativeLength) {
             text->chunkOffset = text->chunkLength;
-            isAccessible = FALSE;
+            isAccessible = false;
             return true;
         }
     } else {
@@ -93,12 +93,12 @@ inline bool uTextAccessInChunkOrOutOfRange(UText* text, int64_t nativeIndex, int
             // Ensure chunk offset is well formed if computed offset exceeds int32_t range.
             ASSERT(offset < std::numeric_limits<int32_t>::max());
             text->chunkOffset = offset < std::numeric_limits<int32_t>::max() ? static_cast<int32_t>(offset) : 0;
-            isAccessible = TRUE;
+            isAccessible = true;
             return true;
         }
         if (nativeIndex <= 0 && !text->chunkNativeStart) {
             text->chunkOffset = 0;
-            isAccessible = FALSE;
+            isAccessible = false;
             return true;
         }
     }
--- a/Source/WTF/wtf/text/icu/UTextProviderLatin1.cpp	
+++ a/Source/WTF/wtf/text/icu/UTextProviderLatin1.cpp	
@@ -100,23 +100,23 @@ static UBool uTextLatin1Access(UText* uText, int64_t index, UBool forward)
         if (index < uText->chunkNativeLimit && index >= uText->chunkNativeStart) {
             // Already inside the buffer. Set the new offset.
             uText->chunkOffset = static_cast<int32_t>(index - uText->chunkNativeStart);
-            return TRUE;
+            return true;
         }
         if (index >= length && uText->chunkNativeLimit == length) {
             // Off the end of the buffer, but we can't get it.
             uText->chunkOffset = static_cast<int32_t>(index - uText->chunkNativeStart);
-            return FALSE;
+            return false;
         }
     } else {
         if (index <= uText->chunkNativeLimit && index > uText->chunkNativeStart) {
             // Already inside the buffer. Set the new offset.
             uText->chunkOffset = static_cast<int32_t>(index - uText->chunkNativeStart);
-            return TRUE;
+            return true;
         }
         if (!index && !uText->chunkNativeStart) {
             // Already at the beginning; can't go any farther.
             uText->chunkOffset = 0;
-            return FALSE;
+            return false;
         }
     }
     
@@ -144,7 +144,7 @@ static UBool uTextLatin1Access(UText* uText, int64_t index, UBool forward)
 
     uText->nativeIndexingLimit = uText->chunkLength;
 
-    return TRUE;
+    return true;
 }
 
 static int32_t uTextLatin1Extract(UText* uText, int64_t start, int64_t limit, UChar* dest, int32_t destCapacity, UErrorCode* status)
@@ -337,7 +337,7 @@ static int64_t uTextLatin1ContextAwareNativeLength(UText* text)
 static UBool uTextLatin1ContextAwareAccess(UText* text, int64_t nativeIndex, UBool forward)
 {
     if (!text->context)
-        return FALSE;
+        return false;
     int64_t nativeLength = uTextLatin1ContextAwareNativeLength(text);
     UBool isAccessible;
     if (uTextAccessInChunkOrOutOfRange(text, nativeIndex, nativeLength, forward, isAccessible))
@@ -357,7 +357,7 @@ static UBool uTextLatin1ContextAwareAccess(UText* text, int64_t nativeIndex, UBo
         ASSERT(newContext == UTextProviderContext::PriorContext);
         textLatin1ContextAwareSwitchToPriorContext(text, nativeIndex, nativeLength, forward);
     }
-    return TRUE;
+    return true;
 }
 
 static int32_t uTextLatin1ContextAwareExtract(UText*, int64_t, int64_t, UChar*, int32_t, UErrorCode* errorCode)
--- a/Source/WTF/wtf/text/icu/UTextProviderUTF16.cpp	
+++ a/Source/WTF/wtf/text/icu/UTextProviderUTF16.cpp	
@@ -126,7 +126,7 @@ static inline int64_t uTextUTF16ContextAwareNativeLength(UText* text)
 static UBool uTextUTF16ContextAwareAccess(UText* text, int64_t nativeIndex, UBool forward)
 {
     if (!text->context)
-        return FALSE;
+        return false;
     int64_t nativeLength = uTextUTF16ContextAwareNativeLength(text);
     UBool isAccessible;
     if (uTextAccessInChunkOrOutOfRange(text, nativeIndex, nativeLength, forward, isAccessible))
@@ -146,7 +146,7 @@ static UBool uTextUTF16ContextAwareAccess(UText* text, int64_t nativeIndex, UBoo
         ASSERT(newContext == UTextProviderContext::PriorContext);
         textUTF16ContextAwareSwitchToPriorContext(text, nativeIndex, nativeLength, forward);
     }
-    return TRUE;
+    return true;
 }
 
 static int32_t uTextUTF16ContextAwareExtract(UText*, int64_t, int64_t, UChar*, int32_t, UErrorCode* errorCode)
--- a/Source/WebCore/platform/text/TextCodecICU.cpp	
+++ a/Source/WebCore/platform/text/TextCodecICU.cpp	
@@ -194,7 +194,7 @@ void TextCodecICU::createICUConverter() const
     UErrorCode error = U_ZERO_ERROR;
     m_converter = ICUConverterPtr { ucnv_open(m_canonicalConverterName, &error), ucnv_close };
     if (m_converter)
-        ucnv_setFallback(m_converter.get(), TRUE);
+        ucnv_setFallback(m_converter.get(), true);
 }
 
 int TextCodecICU::decodeToBuffer(UChar* target, UChar* targetLimit, const char*& source, const char* sourceLimit, int32_t* offsets, bool flush, UErrorCode& error)
--- a/Source/WebKit/UIProcess/CoordinatedGraphics/DrawingAreaProxyCoordinatedGraphics.cpp	
+++ a/Source/WebKit/UIProcess/CoordinatedGraphics/DrawingAreaProxyCoordinatedGraphics.cpp	
@@ -402,7 +402,7 @@ DrawingAreaProxyCoordinatedGraphics::DrawingMonitor::~DrawingMonitor()
 int DrawingAreaProxyCoordinatedGraphics::DrawingMonitor::webViewDrawCallback(DrawingAreaProxyCoordinatedGraphics::DrawingMonitor* monitor)
 {
     monitor->didDraw();
-    return FALSE;
+    return false;
 }
 
 void DrawingAreaProxyCoordinatedGraphics::DrawingMonitor::start(WTF::Function<void(CallbackBase::Error)>&& callback)